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NeilS
1st Mar 2011, 03:59 PM
Prompted by Hughie's Astra Dot abrasive thread and Ern's (rsser) Dry Ice abrasive thread, I have been giving a few different abrasives a 'test run'. Nothing too technical, just integrating them into my normal work flow and noting some times and observations.

This was just a suck-it-and-see on a few abrasives that came to my attention. Any omissions are coincidental and don't imply anything in particular. I'm just sharing what I discovered in my workshop doing what I predominantly do, making bowls and power sanding them to a level acceptable to the galleries where I sell my work, ie to about #400, plus a bit extra if required depending on the piece and the wood. The few exhibition pieces that I make from time to time get extra attention but that is not the level of finish I'm referring to here. I'm just sharing what I found in case it's of any value to anyone else, without any pretense of expertise or objectivity.

With the exception of a brief period of using Noretake's Astra Dot, Norton's Champaign and some Kingspor, I have been using various no-name velcro backed abrasives purchased in rolls from variuos suppliers from which I have cut my own disks. Economical but perhaps not as efficient as some of the newer abrasives or maybe even value for money. So, I thought it was about time to try out and compare a few other options.

For me, efficiency is more important than durability (but not at any cost... :rolleyes: ). By efficient I mean how quickly and predictably I can get to desired level of finish. Cleaning out clogged abrasive, stopping to swap spent abrasive papers, having to go back to eliminte out-of-range renegade grits, having to spend extra time repairing the surface after an overly aggressive prior grit, all come into the efficiency equation and not just how rapidly the abrasive cuts the wood.

A reminder that there are two flexible abrasives grit size standards (ANSI/CAMI in USA & FEPA, the 'P' ones, in Europe). For example #180 in both systems is about 80 microns, whereas the USA #400 is 23 microns but the Euro P400 is only 32 microns. And, should you go from USA #400 to P600 (26 microns) you will be going back to a coarser grit, not a finer one. This needs to be kept in mind if making comparisons or abrasives are being mixed from different manufacturers.

There is a lot of other technical stuff to know about abrasives, none of which I've attempted to cover here.

The abrasives I tried:

My current batch of No-name Alox 2" - all grit sizes
Vince's Blue Flex* 2-3/8" - #100, 150, 220, 320, 400
Vince's Ceramic* 2-3/8" - #120, 180, 220
3M Scuff Brite pads* - aprox #320, #800, and #1200
Vince's Cera~Max* 2-1/2" - #120, 180, 280, 400
Norton's Dry Ice 2" - #120, 180, 240, 320, & 400
Noretake's Astra - single dot - #120
Kingspor - various

* These abrasives also required an interface pad like this (http://www.vinceswoodnwonders.com/Firm%20and%20Soft%20Inneraface%20Pads%20.htm) to fit the standard 2" mandrel.

Next post: How quickly did they finish the job?

Cliff Rogers
1st Mar 2011, 04:05 PM
Watching.

NeilS
1st Mar 2011, 04:05 PM
Starting with the next available grit above #80, each grit was worked through until I got the best finish I could at #400. Very subjective, I know, but from experience I expect that my standard would satisfy most turners. Each piece was inspected under 40x magnification and with a bright LED light after the last two grits to check for any residual scratches not readily visible to the naked eye.

A new set of disks was used for each surface, except for the Dry Ice where I only had one set of each grit. These were gratis so I could include them in the test run, thanks Ern.

The lathe ran at about 1500rpm and the disks at 3000rpm for the lower grits and the lathe progressively slower for the higher grits (down to 250rpm). A very light touch was used.

A separate duration test was conducted and reported in a later post.


Abrasive: Vince's Ceramic Grip to #220

Wood: Oak, Diameter: 9" bowl, Surface: outside, Time: 35 mins + #320 buff for 8 mins, total 43 mins
Wood: Oak, Diameter: 9" bowl, Surface: inside, Time: 30 mins + Vince's Blue to #400to for 20 mins, total 50 mins
Silky Oak, Diameter: 7.5" bowl, Surface: outside, Time: 25 mins + Vince's Blue to #400 for 7 mins, total 32 mins


This ceramic was very aggressive, removing a lot of wood very rapidly but leaving a rougher surface than the grit rating would indicate which then required an effort to remove with the follow up abrasives above #220, and as a result the overall time to completion wasn't that good.

The sample Ceramic Grip kit included #320, #800, and #1200 Scuff Brite pads to complete a piece after the Ceramic #220. I didn't find these pads very abrasive or sufficient to complete a piece on their own. Closer intervals between the grit sizes may have worked better. These pads may have also allowed for renegade lower grits to be re-introduce and to re-scratch the finish, but I didn't have time to confirm this with further testing.

I also found that the white #1200 will burn if allowed to dwell on stationary wood... :((

The Ceramic Grip and Blue Flex 2-3/8" disks and the Cera~Max 2-1/2" disks all provide more abrasive than standard 2" disks (roughly 50% more) which is nice to have, especially on the outside of bowls, but I found them to be too large for the inside of small and medium bowls. They also require an interface pad to run on the standard 2" mandrels. There are some claimed advantages to using these adaptors, including saving the hook surface of the more expensive mandrel and selecting different densities of backing for different applications, but these may not be advantages that are seen as important to every turner.


Abrasive: No-Name Alox

Wood: Blackwood, Diameter: 7" bowl, Surface: outside, Time: 40 mins
Wood: Blackwood, Diameter: 7" bowl, Surface: inside, Time: 43 mins

The coating on the grit quickly wore off the No-Name abrasive but there was no clogging evident. The rate of wood removal began to slow towards the end of each grit. Going by the nominated grit size, the grit intervals were not predictable. With some effort the end result was satisfactory but slow.


Abrasive: Astra Dot + Kingspor

Wood: Mango, Diameter: 10.5" deep bowl, Surface: Outside, Time: 30 mins


I only had 3" disks for these abrasives so only used these on the outside of the test bowl.

The surface left by the #120 Astra Dot (the finest I had above #80) was the roughest of any left by the #120 abrasives. I then proceeded on to the #120 Kingspor which was needed to clean up the rough surface left by #120 Astra Dot. I was, however, reminded how grippy the Kingspor is. Too grippy for me to consider as an option with my fast and light technique. The time to get to an acceptable finish was better than the two previous tests, but not so pleasant getting there IMO.

Running up through the Astra Double after the Single Dots and then onto the finer Champaign may have been a difference experience, but I didn't have those to hand so can't comment on that option.


Abrasive: Dry Ice

Wood: Blackwood, Diameter: 12" platter, Surface: outside, Time: 35 mins
Wood: Blackwood, Diameter: 12" platter, Surface: inside, Time: 30 mins

Quick and aggressive, but loaded up chronically. However, surprisingly it had the best #400 that I tested, doing a good job of removing the #320 grit abrasions and also leaving minimal visible marks itself. The time taken to clean out the clogged abrasive was included in the overall times, which left it under performing despite its rapid rate of the abrasive cut.

The Dry Ice comes as a standard 2" disk, so didn't need any adaptors and would also work quite well inside smaller diameter bowls.


Abrasive: Vince's Blue Flex

Wood: Mango, Diameter: 10.5" deep bowl, Surface: inside, Time: 30mins
Wood: Blackwood, Diameter: 9" bowl, Surface: inside, Time: 35mins
Wood: Oak, Diameter: 8.5" bowl, Surface: outside, Time: 24 mins

The Blue Flex had a firm bite with minimal or no clogging. They did not feel as if they were nearing exhaustion towards the end of each grit and I expect they would kick on for a bit more than just one surface of a bowl of this size. The duration test will give a reading on this. It required my best efforts to get a satisfactory finish at #400 to avoid some fine residual abrasions, the sort that are just discernible with the naked eye under strong angular light. In defence of Blue Flex, they also supply a #280 between the #220 and #320 which I chose to skip when I was buying. The addition of this extra grit may have given a better outcome at #400.


Abrasive: Vince's Cera~Max

Wood: Cherry pine, Diameter: 8.5" bowl, Surface: outside, Time: 23 mins
Wood: Cherry pine, Diameter: 10"diam deep bowl, Surface: outside, Time: 20 mins
Wood: Cherry pine, Diameter: 10" diam dee bowl, Surface: inside, Time: 20 mins

This abrasive is a blend of ceramic and traditional alox. The claimed benefit is the best of "ceramic for long lasting wear and aluminum oxide for even grit consistency".

The Cera~Max worked quickly and smoothly, with minimal or no loading, but again I found that I had to concentrate to eliminate all residual abrasions at #400. There is a #360 disk that wasn't included with the sample pack and expect that this could make a noticeable difference to the quality of the final finish, albeit at some cost to the time required to finish the job. Given the speed of this abrasive, the addition of another grit to more readily get a better finish would add just a little extra time (3 to 4 minutes) and still leave it as the fastest abrasive I tested.

Cera~Max disks are 2.5" diam. My sample pack didn't come with the 2.5" interface pad so they overhung the supplied 2-3/8" adaptors. Had I been able to use the matching 2.5" interface pad I may have got even better results on the speed and endurance tests.


Next post: Durability

NeilS
1st Mar 2011, 04:11 PM
The purpose of this test was to see how long each abrasive make would effectively work or how long before the backing failed. What might still be 'effective' for one person may have long gone past that point for someone else. For this test (but not necessarily how I work) the criteria was to use the abrasive until I could no longer feel a positive bite or until the stream of sanding dust coming off the wood dropped to about 1/3 of the initial volume. The two things usually happened about the same time. The volume of dust coming off the wood was observed at the mouth of the dust extractor hose intake which was positioned next to the work piece. A light coloured wood (Cypress) was selected so the dust from this could be clearly seen against the dark interior of the extractor intake. The outside of the same shallow 20" bowl was used to test all abrasives.

The #80 abrasives were initially selected for this endurance test, but after nearly 45mins on the first disk and about 10mm off the outside of the 20" bowl I gave that idea away. It was becoming an endurance test on me too. So I selected #180 instead, a better idea as this is about the mid-point in the normal sanding range and where the majority of the ground work is done for a good finish. And, all of the #180 abrasives should be predictably rated at about 80 microns, irrespective of the rating system.

Here are the times for the #180s.

Dry Ice #180: 18 mins
Ceramic #180: 18 mins
Kingspor #180: 10 mins
Blue Flex #180: 9 mins
Cera~Max #180: 9 mins
No-Name #180: 8 mins

As I did not have any Astra Dot #180 I ran a separate test with a fresh Astra #120 and compared this to Vince's #120 Ceramic and Cera~Max. All three abrasives were cut to 2"diam so I could run it on my standard 2" mandrel to avoid the interface pad cooking problem experienced during the #180 endurance test run, reported below.

Here are the times for the #120s.

Cera~Max #120: 70 mins
Astra Dot #120: 38 mins
Ceramic #120: 31 mins

In the case of the Cera~Max I gave up before it did. It was willing to keep going, I wasn't! It had made its point and I was ready to go home... :-)

A longer run time was expected at the lower grit, but what was not expected was the significant switch in performance between the #180 and #120 Cera~Max and Ceramic. For want of an explanation, the composition of Cera~Max is predominantly ceramic in the lower grits but progressively switches over to alox in the higher grits. So at #180 the Cera~Max was behaving more like an alox abrasive than a ceramic.

Not obvious from the raw times was the difference in how much wood each of these #120s was removing. The Ceramic and Cera~Max began by removing at least twice as much wood as the Astra. Not surprising given the difference in the amount of grit on each. At about the 13min mark the Ceramic was down to removing about the same as the Astra did initially. And, the Cera~Max kept removing wood at a rate exceeding that of the Astra for the full duration of the test. So the Astra removes wood more slowly but persists for longer than the Ceramic, by a bit, but it didn't start to compete with the Cera~max on rate of removal or duration.

There had been no observed difference in the rate of wood removal during any of the #180 endurance tests.

Another observation was that the Astra Single Dot threw the dust the least distance from the disk of any of the abrasives. This in part came from the dust not clinging to the wood and being slung away. The dot pattern would be the reason for this. As a result the dust extractor inlet was able to capture most of the dust before it escaped. This feature may be important to some.

Two other things to report. In the aborted #80 test run the backing on the Dry Ice disk failed at the 40 min mark. It was the only disk backing to fail during any of the tests. I also had two of the required interface pads cook during the duration test. The velcro layer started to separate from and move on the foam interface layer resulting in buckling and risk of total failure. Admittedly the #180 endurance runs were a harsh test exceeding normal practice, but worth noting anyway for anyone who might push these limits. @$4 a pop it's a consideration.


162950 162951


I had intended to repeat the durability test run on a decent piece of hardwood, but at this point my enthusiasm flagged. The results could be different if I had. Perhaps another time.

Next Post: Emma Chisset and some personal conclusions

NeilS
1st Mar 2011, 04:15 PM
On speed alone, the Cera~Max is very attractive, while its durability excels at the lower grits it sits acceptably along side the other lower priced options at #180. I also quite liked the feel of the Cera~Max on the wood and the finish. The durability of the required interface pads is still a question, as is the size. Those 2.5" disks will need to be cut down to go inside smaller and medium sized bowls. The economics of doing that is another consideration.

The pure ceramic options (Vince's Ceramic and Norton's Dry Ice) sure rip off the wood quickly but leave a surface that requires extra time to tame with non-ceramic abrasives. My results indicated that the overall time to completion wasn't significantly improved by using them. Their extra cost was commensurate with their durability but there is a question over the durability of the Blue Ice backing. Its propensity to clog was also a negative for me.

If speed is not such a factor for someone then Astra Dot is worthy of consideration, especially if you cut the disks yourself from rolls. Using a full set of Atra Single and Double Dot disks may also give a different result. It's non-clogging performance in wet and oily woods is a feature that may be an additional attraction for some turners.

I'm giving Kingspor a miss myself because of its grippy-ness but others may not mind or may even like this.

The abrasive I'm still not decided on is the Blue Flex. I think I need to get the missing #280 that I left out of my order to see if that makes any difference on the overall time to get to a good level of finish. I'm also going to have to give the interface pads more of a trial under normal working conditions.

So, for me, the price/performance sweet spot is looking like Cera-Max, and possibly Blue Flex, with a few questions still to be answered.

Whatever I decide, I don't think I will be staying with my current No-Name abrasives. Yes, cheap but not very efficient.

Your mileage may be different, but hope this has been of some use to you.

And, finally, some words from an acknowledged sanding expert, Bill Neddow,

"just remember, the sandpaper business is very competitive. You get what you pay for. Those extra cents you pay for the more expensive papers translate into longer lasting grit, better glues, backings and velcro and a more consistent grit pattern - which cuts down the potential for those frustrating scratches that suddenly appear at times.

I know of only one shortcut that actually saves money cutting your own disks."

See his article, "Sandpaper: New Grits, New Techniques, and Results of 10 Years of Testing", in Woodturners America, *here (http://www.woodturnersamerica.com/index.php?option=com_content&view=article&id=99:sandpaper-new-grits-new-techniques-and-results-of-10-years-of-testing&catid=65:editorials)*

Paul39
2nd Mar 2011, 12:57 PM
Thank you Neil. This is good information for those of us who would rather sand bowls than test sand paper.

Ozkaban
2nd Mar 2011, 02:56 PM
thanks for an interesting, comprehensive post Neil. I have changed from cheaper papers to mid level stuff like astra dot in recent times and whilst I haven't measured anything, I do feel the longevity outweighs the cheapness. Also it's just plain less irritating to use nicer stuff :cool:

Cheers,
Dave

rsser
21st Jul 2011, 09:57 AM
:2tsup:

Excellent info.

hughie
21st Jul 2011, 10:06 AM
[Thank you Neil. This is good information for those of us who would rather sand bowls than test sand paper.[/



:U you'll get an amen on that one! :2tsup:

robo hippy
27th Jul 2011, 03:29 AM
I forgot a few things on the other abrasive thread, and this might be a good place to add them.

The interface pads. I love the contoured pads from Vince. Use the flat for the outside of the bowl, and the radius edge on the inside. I do stick with a firm pad for grits up to 220 or so, and then some times switch to the soft pads. 120 grit on a firm pad cuts better than 80 on a soft pad.

I have wondered how to do a measured comparative test on abrasives. You would need bowls from the same tree, the same size, and a jig to hold the drill in so pressure would be the same/constant. Also, some sort of a metered thing to make sure drill speed was constant.

If I can get a 3 inch disc inside a bowl, no matter how small the bowl is, I will use it because a 3 inch disc has more than double the surface area.

I have experimented with grit jumps. 80, 120, 180, 220, 320, 400. I have tried the jump from 180 to 260, and didn't like it. Mostly I figure that there will always be some scratches left from the 120, and the 260 just won't get them out while the 220 will.

From talking to Vince, with the ceramic abrasives, there are way less ceramic pieces in the higher grits because the manufacturers figured there wasn't enough benefit in durability vs cost to make it worth while.

I haven't tried out the 3M cubitron discs. Only available in grits to 220, and only available in PSA (sticky back), and not in hook and loop.

robo hippy

STAR
27th Jul 2011, 09:15 AM
Thanks for sharing all this information. I am pleased that I came across it. While I am not into bowls as such I am more interested in learning how to carve large items and then how to finish them as near professionally as I can,

The tools I have are leaving me with a severe disadvantage but your articles, when I get my head around them, might open a few more doors for me.

Thanks for showing a sire with photo's of what you are talking about.

Pete

Tim the Timber Turner
27th Jul 2011, 02:35 PM
If I can get a 3 inch disc inside a bowl, no matter how small the bowl is, I will use it because a 3 inch disc has more than double the surface area.

Hi Robo Hippy

I would suggest that using a 3" pad in a small bowl is not ideal for 2 reasons.

1: Only the outside of the abrasive disc gets any wear. Some turners then take this disc and punch a 2" one from the centre.

2: A smaller 2" pad better follows the contours of a small bowl.

A couple of observations.

A larger pad will not get as hot as there is a larger mass to absorb the heat being generated.

A larger pad will give you a smother surface on platter forms. It tends to take off the high spots and not remove wood on the softer parts.

I tend to use a 6" pad on large bowls and platters.

I hope this adds to the discussion.

Cheers:)

Tim

robo hippy
27th Jul 2011, 03:31 PM
When sanding bowls, on the outside, I use mostly the center part of the disc. On the inside, because of the concave shape, I sand with the edge of the pad. When I am done with the disc, I might get a 1 inch disc out of the center, but most of the time the disc is totally worn out.

As far as the 2 inch disc fitting better than the 3 inch disc, that is true if the walls are steep, and the transition is sharp. On a more open form, all you have to do to get the edge of the disc into the transition is angle the disc a bit, rather than having it at 90 degrees to the bowl.

Not sure about the 3 inch disc running cooler. At the same rpm, the 3 inch disc will have a higher feet or meters per minute than a 2 inch disc.

robo hippy

NeilS
2nd Sep 2011, 05:03 PM
FenceFurniture organised for some Jost abrasives to be sent to me for evaluation.

He has a separate thread running here (http://www.woodworkforums.com/f9/jost-abrasives-first-impressions-excellent-140243/) on his evaluation of these abrasives for flat work. I'm concentrating here on their use for power sanding in woodturning.

I received from Jost some samples of their 2" Superpad P (P60, P100, P120, P180 and P400) and 2" Superfinishing SG and SG-2 abrasive pads (SG 600, SG-2 1800, SG-2 2500 and SG-2 3000).

The first thing I did was repeat the durability test (see post No 4) using the same test piece of wood (there was still some thickness left on it) using the same protocol as outlined above.

I began with the P120 pad to see how well it performed against the best performer last time, which was the Cera~Max #120. The Superpad P120 cut aggressively and continuously without any apparent loss of cutting power for 75 mins. As before with the Cera~Max, I gave up at this point. The disk was willing to keep going, I wasn't! It had made its point. It was at least as good as the Cera~Max.

I then did the durability test on the Superpad P180 to see how well it performed against the previously tested #180s. The value of doing this is that all #180 abrasives should be predictably rated at about 80 microns, irrespective of the rating system (US or Euro).

The Jost Superpad P180 lasted just 6.5mins when it abruptly stopped doing anything at all. Cleaning it with the rubber stick didn't make any difference at all. It was as dead as any abrasive I've ever attempted to use! The poorest performer of any of the #180 abrasives tested.

So, very mixed results on durability.

Because of the big drop in performance between #120 and #180 with both the Jost and Cera~Max abrasives I decided to run the durability test on the Kingspor #120 abrasive (I had already done it for the #180) to get more perspective on the expected difference in performance over that jump in grit sizes. The Kingspor went for 45 mins before dropping down to the designated half-output performance level. The output was only ever half as good as the Jost, from start to finish. Perhaps about the same as the Astra Dot. So not as good as Jost and Cera~Max but better endurance than the Astra Dot and Vince's Ceramic.

I should repeat the same durability test on hardwood, but not today!

Yet to do the test run for the Jost on 'time through to ready for finish'. I'll do that over the next few days.
.

rsser
2nd Sep 2011, 05:15 PM
75 minutes = an exhaustive test ;-}

Thanks for the post Neil.

Odd how different the results were for the 120 and 180.

NeilS
5th Sep 2011, 04:32 PM
The first thing I noted when I received the Jost abrasives samples was the jump in grit sizes from #180 to #400. Most of us woodturners would also use #240 and #320 to get from #180 to #400.

Jost does make a #220, #240, #280 and #320 abrasive in their Superpad P Useit line, so I'm not sure why none of those were included with the samples. Perhaps they don't make them in the 2" size. Anyway that is what I received, so I proceeded to see how that combination performed.

The lower grit sizes worked quickly, but as anticipated, the #400 failed to effectively remove all of the lower grit marks. I was surprised how much the #400 was able to do, but it became apparent that it was going to take forever (and maybe a second new disk) for it to completely remove all of the lower grit marks to my satisfaction. So I stopped when progress slowed right down.

Wood: Blackwood, Diameter: 9.5" bowl, Surface: inside, Time: 26mins

Next I added in two of Vinces Blue Flex abrasives to fill the gap between the Jost #180 and #400 to see what difference that would make.

Wood: Native Cherry, Diameter: 9.5" bowl, Surface: outside, Time: 22 mins

With the addition of the extra grits I got a scratch free (to the naked eye) result and the time taken to get there was right up there with the best performer, Cera~Max.

Out of interest I then went on to the Superfinishing SG #600 and SG-2 #1800 'polishing' pads. The results were OK, but I still felt the need to use EEE to complete the job to my satisfaction. Using EEE after #400 achieved the same result as the SG and SG-2 followed by EEE.

Some other observations.

These Jost abrasives are specifically designed for optimal removal of dust while working on flat work. Their claimed efficiency and durability is probably based on the effective and continuous removal of dust from the working surface. To do this they need power equipment that sucks the dust away through the hook-n-loop backing system. To my knowledge there are no rotary sanders of the type that woodturners use whaih do that.

Without any means of removing the dust from the hook-n-loop system I found that there was a heavy buildup of dust in the hook area of my pads. So much so that it became increasingly difficult to attach new abrasives pads without spending time vacuuming the hook area free of dust between abrasives. Without an effective solution I would find this unworkable.

As with most abrasive disks, I found that I got burning if I let the edge of the abrasive disk come in contact with an adjacent area of wood. It seemed to me that this was more severe than normal, perhaps because the rim is in effect serrated from the hole pattern which cuts through the edge. Worth noting, but avoidable with care.

The other consideration is cost. I don't have any numbers on that at this stage. FenceFurniture may at some stage have more on that in his thread on the Jost abrasives. In my view it would need to be in the bulk purchase range of 12c to 15c per 2" disk to compete with similar performing abrasives and for there to be an economical solution for the dust extraction through the hook-n-loop on a rotary sander.

rsser
5th Sep 2011, 04:52 PM
Thanks for the update Neil.

The VM inertia sander has a vac connection in the handle but it can only draw from the pad perimeter.

stuffy
5th Sep 2011, 05:47 PM
Thanks Neil.

I wouldn't mind trying one of these sanders if they become available in Australia.

Metabo Compact Orbit Sander | Metabo Sanders (http://www.highlandwoodworking.com/metabocompactrandomorbitsander.aspx)


Best wishes

Steve

NeilS
5th Sep 2011, 10:24 PM
Thanks for the update Neil.

The VM inertia sander has a vac connection in the handle but it can only draw from the pad perimeter.


Thanks Neil.

I wouldn't mind trying one of these sanders if they become available in Australia.

Metabo Compact Orbit Sander | Metabo Sanders (http://www.highlandwoodworking.com/metabocompactrandomorbitsander.aspx)

Best wishes

Steve

Ern and Steve - Yes, from what I can see, the best that any rotary (inertia or powered) sander can do is suck dust through a hood that surrounds the pad. Whereas the limited travel on an orbital sander head allows for ducting to be constructed through the hook pad.

Must admit I've never tried using an orbital sander on woodturning. I anticipate it would be relatively slow going. Must have a go with my little mouse sander to see what happens.

robo hippy
10th Sep 2011, 03:25 AM
Neils,

Excellent article, and you should submit it to the magazines.

I am wondering if speed would factor in to how the abrasives wear. I am a fan of the slow speed sanding, with my drill running at 600 or less rpm, and the bowl turning at 20 rpm or so. My bowls are warped, so no way could I sand over about 30 rpm, and some warp so bad, I have to use the spindle lock. I have found that my drills last a lot longer before the bearings are shot if I use slow speeds. When sanding at high speeds, I would get 300 plus bowls (all sizes from 3 to 16 inch diameter), and with the slow speeds, they would go to 400 plus bowls. My abrasives seem to last a bit longer than yours do as well.

One contributing factor that is different from your methods is that I do the LDD soak: Mix of 1/2 cheap brown hand dishwashing detergent, and 1/2 water, soak for 24 hours, rinse off lightly, and allow to dry. The LDD definitely makes the sanding easier.

robo hippy

NeilS
12th Sep 2011, 04:10 PM
Thanks for your contribution Robo Hippy. Always good to get another take on the topic, especially if it is coming backed with extensive experience, which is the case with your contributions.

I've listened to and read on what the various experts have had to say on both the fast and slow methods of sanding. After trying both my concession to the slow method is that I now slow down progressively as I get into the finer grits.

At some stage I may do a controlled comparative test of fast vs slow, but not for a while. My back orders and to-do-list are demanding my attention on other matters in the workshop.

robo hippy
13th Sep 2011, 04:30 PM
Another thought on sanding that I had. Someone needs to invent an articulated type of arm for holding the sanders. There are a number of that type of hollowing systems. Shouldn't be too difficult to make one that would hold the sanders, and have a universal head on it so you could do both inside and out side. I could sit in my easy chair.......

robo hippy

rsser
13th Sep 2011, 05:06 PM
LOL. If only.

Not sure though what you mean by articulated.

The VM, Skilton and Vermec inertia units all have angulable heads.

Vermec have a rather interesting deep hollowing sander head. In my imagining it shouldn't work but V. don't release stuff for the market to test IME.

Steve, yes I'd like to see a test of that. A 3" interface pad is offered by Sanding Tools / Power Sanders & Accessories / Metabo Random Orbit Sander (http://thesandingglove.com/Metabo-Random-Orbit-Sander.asp)

Harking back, the Dry Ice needs high speed and light touch; I'm sure that Neil allowed for that.

Tim the Timber Turner
13th Sep 2011, 05:14 PM
Another thought on sanding that I had. Someone needs to invent an articulated type of arm for holding the sanders. There are a number of that type of hollowing systems. Shouldn't be too difficult to make one that would hold the sanders, and have a universal head on it so you could do both inside and out side. I could sit in my easy chair.......

robo hippy

Check out the hollow form sander from Woodcut Tools in NZ. It has a small articulated head and takes a 30mm, 50mm or 75mm pad.

Designed to sand the inside of hollow forms.

Cheers

Tim:)

rsser
13th Sep 2011, 05:37 PM
RH doesn't do hollowing but anyway:

Vermec dh sander, not articulated:

http://vermec.tripod.com/PDFs/Ulitmate_Sanding_Head.pdf

I couldn't find Tim's ref to a WC hollow sander in http://www.shop.woodcut-tools.com/media/Catalog%20&%20Prices/Catalogue%2007.pdf

vk4
13th Sep 2011, 05:42 PM
the variation between 120# and the 180# could indicate that the GRIT is from 2 different suppliers, .

the hardness of the grain can vary due to factors involved in the manufacture, apart from garnet , all other abrasive grit is manufactured.

Aluminum Oxide is made from Bauxite ( if further refined you get ALUMINUM), Zirconia is another process along from Aluminum Oxide , and Ceramic is a separate material in itself.

The hardest is called CBN, carbon boron nitrate which is comparable to DIAMOND in hardness, and is a very specialized cutting abrasive.

Jeff
vk4

NeilS
13th Sep 2011, 07:57 PM
I could sit in my easy chair.......

robo hippy


.....:U

If they can get them to write why not sand?


181694
.

Tim the Timber Turner
13th Sep 2011, 10:48 PM
I couldn't find Tim's ref to a WC hollow sander in http://www.shop.woodcut-tools.com/media/Catalog%20&%20Prices/Catalogue%2007.pdf

Try this.


Woodcut Tools Ltd > Pro-Forme Flexi Sander (http://www.shop.woodcut-tools.com/product.php?xProd=283&jssCart=bb9f51ba487b73886fcbc3463746cf8f)

Cheers

Tim

robo hippy
14th Sep 2011, 02:38 AM
This is what I meant by an articulated hollower. The arm has a couple of joints in it. They aren't for big forms, say up to 12 inched deep by the heavy duty ones, but it only takes finger tip pressure to move it. Something to support the weight of the sander, and be easy to move.

Monster Lathe Tools - Mini Monster Hollowing System (http://monster-lathe-tools.com/cart.php?target=product&product_id=274&category_id=63)

I have never tried one of the inertial sanders, or the flex shaft sanders.

robo hippy

FenceFurniture
15th Oct 2011, 11:19 PM
G'day Neil, somehow I got disconnected from this thread, and didn't realise there were some answers required. I'm not sure of the grits available for turning, but it would seem odd if the jump is from 180 to 400. It may have more to do with what was available, as these turning abrasives are a special run for a German retailer (I think twice per year).

I read in the forum just recently that going up the grit sizes in small increments is actually less work, and less consuming on the abrasives. It makes sense to me, and I tried it - just a quick hit of each abrasive in smaller jumps, and the result was the same and quicker. It does of course mean stocking more grits, but less use of each (i.e. more bucks to stock up, but less bucks per bowl or whatever).

Regarding cost: I'm pretty sure that I was told that both versions are the same price. I have worked out with diagrams and shapes in Excel that I can get 93mm Deltas for about 10.5 cents each, and 90mm discs for about 14.5 cents each. I've just done a diagram and you'd comforatbly get 38x 50mm discs from a metre of 115mm abrasive, and that would make them 5.5 cents each for grits 120-600. I don't know what formats the turning abrasives are available in.

If anyone wants to know more then ask away and I'll find out - now's the time because I'm launching a GB on conventional Jost abrasives this weekend.

I must say that if they are doing a special run of turning abrasives for the German retailer then the consumers would have to be using dust extraction - otherwise you'd do less stamping work, and omit the holes. Now IF this is the case then the abrasives would last much, much longer with extraction, and stay cooler, and perhaps this is the whole point behind the exercise.

Following on from that, has anyone ever used (say) a Festool Rotex 90 (http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=de&tl=en&u=http%3A%2F%2Fwww.kisling-gmbh.de%2Fueber_uns%2F&act=url) for turning-sanding? It would only do shallower bowls internally, but should be able to cover most exteriors. There is a Supersoft pad available, and it's rotary motion is 250-520 rpm with an eccentric oscillation of 3500-700 per minute through a 2mm stroke. Also, I would have thought that that random oscillations would give a better finish in less time - the times I'm looking at in this thread seem extraordinarily long compared with flat sanding. Then again, I could easily be talking through my hat here, because I know nothing about turning, or any of the circumstances that your weirdo world can produce!.

Indeed, perhaps it's time Festool had a look at the plight of turners, as you all seem to go through your drills at a fair old rate. If they did ever produce one you can bet it would be crackajack (and not cheap).

Regards, FF

rsser
16th Oct 2011, 08:33 AM
As Steve pointed out a small Metabo ROS is offered in the US for sanding bowls. It uses pads that are larger than 3" but an adapter pad to bring the size down to 3" is available. I can't say how much better than power or inertia sanding it might be.

There's sanding to remove tool marks and there's sanding to finish. The first can take a lot of time if your tool technique isn't brilliant.

FenceFurniture
16th Oct 2011, 10:53 AM
Thanks for clearing that up Ern. As you know, I like to do a bit of research, particularly if it can solve a problem (not necessarily mine), and so I went looking for a 230v version of the Metabo on their German site. No go. It would seem very odd if they only made a 110v version. Anyway I sent them an email so will see what happens.

Christian Jost tells me that he does a couple of hours sanding every day (?) and I suppose that they probably have most sanders on the planet there for testing the suitability of their abrasives. He may be able to shed a bit of light, or perhaps put me in kontakt with German retailer. The point being that the retailer wouldn't be getting a special run if they didn't sell, so the consumers must have some sort of solution to this, and that must surely revolve around dust extraction.

With the light that you've thrown on the sanding techniques here, it only makes me think even more how necessary dust extraction must be for this kind of sanding. Sanding out tool marks surely means that the whole surface has to be taken down to the bottom of the tool mark (unless you want an undulating surface) and that would means LOADS of dust. It must go everywhere! I think I read someone saying that they use a Big Gulp with a fan to blow into it, but it would be better to get the dust at the source.

If you have any more info that you think might be useful.....

Cheers, FF

rsser
16th Oct 2011, 11:16 AM
Yes, I run an air/con behind me pushing the dust from the piece into a Big Gulp attached to a 2hp dusty. Then there's an air scrubber as well and for woods that ping the sinuses a filtered visor!

And time spent refining the surface of the wood with clean cuts or scraping pays dividends in reducing sanding time and hazard. Sanding is prob. the part of turning that most turners like the least; it's time consuming; if you're not careful you can lose detail or get a rippled surface on timbers with wide grain spacing.

FenceFurniture
16th Oct 2011, 12:18 PM
Some progress on the Metabo sander - they're available in the UK (http://www.powertooldirect.co.uk/metabo_sxe400_random_orbital_sander_240v_onl-p-77459.html) as a 240v version for 70 quid ex VAT which is about $110.

FenceFurniture
16th Oct 2011, 12:57 PM
Couple of things here (http://www.woodturnerscatalog.com/store/Abrasives___Sanders?Args=) including a Sorby Articulated jobbie.

Then there's Kirjes offering from Stiles & Bates (http://www.stilesandbates.co.uk/product.php/section/7059/sn/KJ100K) which also has a dust extraction handle (http://www.stilesandbates.co.uk/product.php/section/7063/sn/KJ211).

NeilS
19th Oct 2011, 08:06 AM
Apologies for the delay in getting to this one, Nick.

Since my last post on this thread I tried the Jost abrasives out on my small B&D Mouse sander, the nearest thing I had to the a small footprint orbital sander.

The verdict, it worked a treat in terms of keeping the abrasive dust free and cutting but it was just so s-l-o-w compared to rotary sanding.

Perhaps the Metabo would be quicker. I read that it goes up to 10,000 rpm no load and 6,000 rpm with load. Not sure what rpm the little B&D does, so there may be a difference there.

The rotary sanders like the Kirjes with the dust extraction hoods will remove some of the dust that is slung off but do nothing for removing the dust directly from the abrasives itself.

If dust minimisation is more important than time then something like the Metabo with the Jost abrasives would be a good combination.

That price per 50mm disks is very competitive.

rsser
19th Oct 2011, 12:56 PM
Can't imagine that you could profitably use a ROS with the piece spinning, esp. when a '#60 gouge' is needed.

For fine finishing with the piece stopped, perhaps.

I've never warmed to inertia sanders but recall Raffan saying at a demo that effectively they punched above their weight by about 2 grits. Power sanding is my pref. as I'm impatient at this stage of the process but appreciate it can cause probs.

Thanks Brett for finding that UK source of the Metabo. The price is too rich for me to justify having a play.

As for the hazard, there are folks who wet sand to keep the dust down. Tried this once on Blackwood and my assessment was that it dulled the chatoyance on that piece. Other woods don't have that so it remains an option.

Tim the Timber Turner
19th Oct 2011, 01:24 PM
I sand all my large platters with a 6 inch ROS with the lathe turning.

I use a Metabo with both a 2mm and a 6mm orbit.

The advantage is a perfect finish that will take a gloss finish with no ripples.
Also no dust if hooked up to a shop vac.

The disadvantage is it's hard on the arms holding the ROS on the work and keeping the cord and hose out of harms way.

Cheers

Tim:)

rsser
19th Oct 2011, 01:45 PM
Interesting; thanks.

Can see the advantage with platters. Have struggled with scrapers and a short straight edge there.

Shallow bowls and a 3" pad on a ROS?

Tim the Timber Turner
19th Oct 2011, 02:12 PM
Shallow bowls and a 3" pad on a ROS?

Maybe.

On most ROS the handle gets in the way.

Small pad sanders don't have much grunt.

The big advantage would be dust free sanding with a shop vac.

:)