Sanding technique

[Grumpy John]

I don't seem to have any trouble when sanding hardwoods such as Blackwood, redgum, burls even banksia, but when it comes to the softer woods i.e. Cedar, Blue Spruce etc I seem to get a ton of fine scratches.
I'm currently working on a bowl which I think could be Oregon (confirmation would be appreciated) and it's driving me nuts trying to get rid of sanding marks. I've tried hand held, rotary (powered and unpowered), I throw the paper away the minute it becomes the slightest bit clogged. I blow the piece down with compressed air to get rid of dust, I alternate direction between grits and I've tried sanding sealer between grits. I don't want to oversand because ridges will develop due to the difference in hardness between growth rings. I've bugger all hair as it is and I don't to tear any more out stressing over these damn scratches.

[DJ’s Timber]

What grit are you starting with, then what order of grits are you going up in?

[Grumpy John]

What grit are you starting with, then what order of grits are you going up in?

100, 120, 180, 240 I haven't gone past 240 yet. I go back 2 grits then start again. I blow down with compressed air between grits and also change lathe direction.

Note: Going off the watch the footy now, be back at 1/4 time :D

[DJ’s Timber]

I reckon you need to add another grit in between 120 and 180, it's too big a jump for softwood IMO

[Grumpy John]

O.K. I'll try a 150 grit. thanks DJ.

[Cliff Rogers]

I also have 150 in that gap but I now try to use a very fine shear scrape so I can start at 180 or 240.

[Swino]

I had the same difficulties with a piece of Coachwood earlier in the week. No matter what i tried I could not get rid of very fine scratches that were visible in some lights. I ended up hand sanding from 240 through to 600 with the grain - the scratches are still there but can't be seen now.

The guys at the wood turning club gave me a few reasons for this occurring:
- Softer wood
- Paper getting too hot during sanding
- Pressing too hard

I hope this helps.

[bowl-basher]

John
I found that a good coat of nitro cellulose sealer was a big help on softer woods
Regards
Bowl-Basher

[Skew ChiDAMN!!]

If there are minor, but obvious scratches that go against both the grain direction & the sanding/rotation direction, I'll stop the lathe and hand-sand along the grain. Usually, when I start the lathe and resume normal sanding with the same grit, that removes the scratch without needing to drop back a grit.

It's just a case of catching them when they first appear, not a grit or two later.


I also have 150 in that gap but I now try to use a very fine shear scrape so I can start at 180 or 240.

I don't think I've ever started under 180!

Sometimes, in case of really, really pernicious tear-out that I can't turn out I'll drop down to a gravel rash combo, but that's only as a "tear-out free chisel," not for finish sanding.

[Cliff Rogers]

... I don't think I've ever started under 180! ....
I'll have to send you a piece of raintree. :D

[Sawdust Maker]

I very rarely start below 60 :D

[Cliff Rogers]

I very rarely start below 60 :D
Only 'cos it is hard to find 36 in velcro backed. :p

[jefferson]

Skew,

I'll save you a small piece of redgum fiddle back and will see whether you can start on 180 grit! It tears out with even the sharpest of scrapers.

Jeff

[Skew ChiDAMN!!]

I'll have to send you a piece of raintree. :D

Yes please! :D:p

[robutacion]

John
I found that a good coat of nitro cellulose sealer was a big help on softer woods
Regards
Bowl-Basher

Yeah...! I like to use that stuff also for the same reasons.

I have also found sometimes steel wool solves the problem!

Cheers:2tsup:
RBTCO

[OGYT]

When I sand soft wood, I never skip a grit except 240, because it always seems to show up a bit later. I keep the following grits on hand. 80,l00,120,150,180,220,280.320,400,0000steel wool,600, and brownpaper sack. Reversing the lathe between grits, and sanding with the grain before going to the next finer grit. Light pressure, low rpm, and being careful will help to keep the "moguls" from appearing. An old furniture maker told me..."Let the sandpaper do it's work... don't force it."
I have Micromesh pads also, but don't use them on anything other than pens.

[Grumpy John]

Thanks for getting things back on topic Al. I'm not too sure about using steel wool after reading this (http://www.woodworkforums.ubeaut.com.au/showthread.php?t=91919) thread.

[Cliff Rogers]

I'll have to send you a piece of raintree. :D


Yes please! :D:p
I'll dig something up & PM you for an address. :2tsup:

[NeilS]

I also have 150 in that gap but I now try to use a very fine shear scrape so I can start at 180 or 240.

I also have #150 and also spend a lot of time shear scraping so that I can start higher, BUT.....:)

[bellyup]

I think I can see your problem, you're becoming distracted and not concentrating - she is in the bottom corner of photo #7!! :U

[Grumpy John]

I think I can see your problem, you're becoming distracted and not concentrating - she is in the bottom corner of photo #7!! :U

I wish it were that easy :no:.

[Skew ChiDAMN!!]

I still recommend stopping the lathe and hand-sanding along the grain between each grit change. It should only take a couple of passes.

If you run your finger across the grain and can feel the hard-grain (ie. the start of corrugations,) simply take a bit of extra time sanding those along the grain, with a bit of sandpaper wrapped around the tip of your finger.

At the lower grits it doesn't really matter if you sand the hard-grain a bit too much, and form a minor depression, as the next grit (with the lathe running) will flatten the softer wood quickly.

But it's a different story at higher grits, where the paper is "polishing" the wood rather than shaping... then you gotta take great care to keep the surface flat.


BTW, I think you're right about it being Oregon. It's rather pale, most Oregon I've seen is more pink/orange/yellow. But it does have a lot of colour variation and that grain is certainly right.

[wm460]

I think I can see your problem, you're becoming distracted and not concentrating - she is in the bottom corner of photo #7!! :U


:rofl::rofl::roflmao:

[Ed Reiss]

John, the solution is simple...keep the paper moving and don't bear down on it. Took me a few years to figure that one out and it works !!!

Give it a go, I think you'll be surprised.:2tsup:

[eisbaer]

i agree with what's been said. My usual process with woods like this (raintree being the best and most painful example) is shear scraping, sanding sealer and hand sanding. Also helps to really scrutinise between grits with a bright light and a very close examination to make sure you're getting rid of scratches at each step.

I use a small led torch to check now as my workspace hasn't got the best lighting. Wiping down between grits is a must also to avoid more scratches from the sawdust. Hope that helps :)

[Grumpy John]

A big thank you to Skew who was kind enough to run me through his sanding technique personally. The wet sanding worked a treat BTW. :2tsup: