Thread: Things you do when you own a surface grinder..

A couple of photos of some parallels I have been grinding for PDW. He gets a few things cast from time to time which are candidates for grinding. The trouble with these longer items is the overhang on the end of the mag chuck. This can lead to a few deviations in flatness. I have a plan to sort out that problem with a new 600mm Eclipse chuck that PDW lugged back from Sydney..

First and second photos are a bit out of focus but shows the high-spots being ground first:

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One thing you have to be wary of grinding those parallels on the mag chuck is the mag chuck may suck down any bow in them, and it bows straight back up when you release them...

Originally Posted by .RC.

One thing you have to be wary of grinding those parallels on the mag chuck is the mag chuck may suck down any bow in them, and it bows straight back up when you release them...

That's when you start the flip and repeat game... flip grind, flip grind, flip grind....

Or..

Double sided tape, thin coat of layout blue, skim and just remove the layout blue, flip and do side two with the chuck powered.

I agree grinding everything can get addictive. Now you need a better indicator with sub micron resolution....

Originally Posted by .RC.

One thing you have to be wary of grinding those parallels on the mag chuck is the mag chuck may suck down any bow in them, and it bows straight back up when you release them...

Tell me about it! It's a trap for young players (me). The overhang also creates quite a bit of springyness.. I checked my notes and one of the parallels was flat to 0.005mm along its 550mm length. The 0.005mm was because of the spring on the ends.

One quickly learns the old feeler gauge trick and residual magnet force to help get things flat - especially thinner parts.

.RC. and others - please make any suggestions you have - and post your own projects..

Below is a gib I am making for the Deckel. It was bowed like a banana. Feeler gauges got it to 0.01mm. I figure scraping is next. It blues up to about 2/3ds of its length.

.RC. how flat does an item have to be to blue up its entire length?

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Nicely done.

I agree, just flipping a part will leave you standing there until the cows come home, and if a part is sucking down you either need to shim the bow in the part, or sometimes I will set it in a grinding vice, grind one side flat, and then put that (now flat) side down to grind the other side parallel.

Another thing to remember is that with permanent magnet chucks that most of us use they don't have to be either on or off, and you can bring in just enough magnetism to hold the part. It's not something I like to make a habit of, as it can be a game of Russian Roulette, but it is certainly a trick to remember. The other day I wanted some parallels as accurate as possible for some scraping setups, and they kept sucking down about 1 um, so I was chasing my tail around a bit. They were hardened and quite hard. In the end I pivoted them on the surface plate to find the high spots, and stoned down the offending humps to get one surface pretty flat so I could grind and match them accurately.

Originally Posted by variant22

Tell me about it! It's a trap for young players (me). The overhang also creates quite a bit of springyness.. I checked my notes and one of the parallels was flat to 0.005mm along its 550mm length. The 0.005mm was because of the spring on the ends.

One quickly learns the old feeler gauge trick and residual magnet force to help get things flat - especially thinner parts.

.RC. and others - please make any suggestions you have - and post your own projects..

Below is a gib I am making for the Deckel. It was bowed like a banana. Feeler gauges got it to 0.01mm. I figure scraping is next. It blues up to about 2/3ds of its length.

.RC. how flat does an item have to be to blue up its entire length?

IMG_1097.jpg IMG_1103.jpg

Hi Anthony,

When you scape the gib, you don't really want it to be flat, you want it bellied a bit, Phil could probably tell us how much, but if I recall correctly, it should sit on the ends, and be slightly hollowed in the center.
There's a video somewhere of RIchard King straightening a gib by hand, just bending it.

Ray

Originally Posted by RayG

That's when you start the flip and repeat game... flip grind, flip grind, flip grind....

Or..

Double sided tape, thin coat of layout blue, skim and just remove the layout blue, flip and do side two with the chuck powered.

I agree grinding everything can get addictive. Now you need a better indicator with sub micron resolution....

I have a few micron indicators. A nice new Mitutoyo and a Mahr Millimess sit in my cabinet. I try to keep them boxed up as they tend to guarantee I will stand in front of the grinder for far too long. With grinders it seems too easy to fall into the trap of perfect micron accuracy for parts that do not even need 0.01mm.

You have reminded me to ask about a source for decent double sided tape?

With the gib strip pictured above it was an exercise of grind, flip, grind, flip etc. I was thinking it would be faster scraping down the high spots with the Biax than chasing the bow. I went the feeler gauge route and that worked out OK. But still a lot of work to go.

Unfortunately my blue tends to wash off with the coolant. Sharpie does a great job - but wont apply over the blue! I tend to outline the blue with sharpie which half does the trick.

Originally Posted by Pete F

I agree, just flipping a part will leave you standing there until the cows come home, and if a part is sucking down you either need to shim the bow in the part, or sometimes I will set it in a grinding vice, grind one side flat, and then put that (now flat) side down to grind the other side parallel.

Agreed. I had that experience with the gib. Even though it is a good 1/2" thick it was sucking down. The feeler gauges did the trick to get it half OK. I was however running out of feeler gauges the right thickness.

Originally Posted by Pete F

Another thing to remember is that with permanent magnet chucks that most of us use they don't have to be either on or off, and you can bring in just enough magnetism to hold the part. It's not something I like to make a habit of, as it can be a game of Russian Roulette, but it is certainly a trick to remember.

The semi-residual magnetic approach worked well to get some of the bumps out. I was not game enough to turn off the magnet entirely with just the residual running. About half strength still gave it a nice amount of stick and reduced bow.

Originally Posted by Pete F

The other day I wanted some parallels as accurate as possible for some scraping setups, and they kept sucking down about 1 um, so I was chasing my tail around a bit. They were hardened and quite hard. In the end I pivoted them on the surface plate to find the high spots, and stoned down the offending humps to get one surface pretty flat so I could grind and match them accurately.

Interesting approach. I have not achieved a perfect match grind yet. It's on my list.

I have generally (excepting post 1 above) been working on parts that are quite long (550mm+). It makes grinding challenging because I am close to the full extents of my grinders travel (about over 620mm). I'm looking forward to the new mag chuck. I will grind the table, then bottom of chuck, then top. Hopefully that gives me a nice platform for these sized parts.

I'm hoping PDW makes some patterns to cast boxes and some squares at some point. He cast straight edges (600mm and 1100mm) recently - which turned out real nice (below - un-ground). I have the perfect squareness testing instrument with acclaimed accuracy to 50 millionths. Useful for getting squares and boxes right. I might have to use it in my 20 degree lounge room however.

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Originally Posted by RayG

When you scape the gib, you don't really want it to be flat, you want it bellied a bit, Phil could probably tell us how much, but if I recall correctly, it should sit on the ends, and be slightly hollowed in the center.
There's a video somewhere of RIchard King straightening a gib by hand, just bending it.

Hi Ray,

Yeah the gib needs to he high on the ends. Relieved in the center. I had the PM guys (Deckel area) tell me while back . I straightened my Deckel gib by hand.. The problem is that I am completely out of travel with it. I need to give the Z a proper scrape and alignment. I was thinking of sending to Phil.

I scraped the old gib to get the Z better. It has the last 1/4 at each end contacting on my plate. Center is relieved back. It took me hours upon hours! I still get knee rock - albeit no where near as bad. A new gib is what's needed in the interim.

I thought I had a photo of it when I finished scraping with the blue but can't find it.

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Hi Ray,

Originally Posted by RayG

When you scape the gib, you don't really want it to be flat, you want it bellied a bit,

I've no idea which gib Anthony is talking about but wouldnt you only belly gibs that never leave their way? The Z on my mill never leaves the ways but the X can. (granted its a whole nother level of mill to Anthony's) Can I assume Deckle gibs dont do this?


Stuart

I was however running out of feeler gauges the right thickness.

I guess you could grind a score mark in them and snap them down smaller, but yeah, I hear you regarding not seeming to have enough at times! I bought some very cheap feeler gauges somewhere in my travels (I think Hong Kong?) and busted them out of their holders that I use for shims. I'm sure they can be bought for peanuts on ebay and they're very handy to have as they're much cheaper than buying dedicated shim stock. I even have a box of (relatively expensive) shim stock, yet tend to use the feeler gauges when I can. When I again run low I'll just buy some more and break them apart again. Whether they're truly "accurate" in terms of what they're marked as I can't say, probably however. Nevertheless it's always been a case of needing something "about that thickness" to fill a gap

Originally Posted by Pete F

I guess you could grind a score mark in them and snap them down smaller, but yeah, I hear you regarding not seeming to have enough at times! I bought some very cheap feeler gauges somewhere in my travels (I think Hong Kong?) and busted them out of their holders that I use for shims. I'm sure they can be bought for peanuts on ebay and they're very handy to have as they're much cheaper than buying dedicated shim stock. I even have a box of (relatively expensive) shim stock, yet tend to use the feeler gauges when I can. When I again run low I'll just buy some more and break them apart again. Whether they're truly "accurate" in terms of what they're marked as I can't say, probably however. Nevertheless it's always been a case of needing something "about that thickness" to fill a gap

Instead of feeler gauges, I use brass shim stock, you can usually buy packets of assorted sizes for $20-30 from the local auto parts places.

This stuff.


One thing I want to try one day is to grind a taper into some spring steel shim, I have heaps of 15 thou and 20 thou spring steel shim, ( I use it for making hand saws) . I'm thinking I'd grind it to taper from 20 thou to 2 thou over 3 or 4 inches. Slice it into strips and use it as wedges to shim up uneven parts. Probably wouldn't work on really wide flat thin parts. Back to double stick tape for those.

Originally Posted by Pete F

I guess you could grind a score mark in them and snap them down smaller, but yeah, I hear you regarding not seeming to have enough at times! I bought some very cheap feeler gauges somewhere in my travels (I think Hong Kong?) and busted them out of their holders that I use for shims. I'm sure they can be bought for peanuts on ebay and they're very handy to have as they're much cheaper than buying dedicated shim stock. I even have a box of (relatively expensive) shim stock, yet tend to use the feeler gauges when I can. When I again run low I'll just buy some more and break them apart again. Whether they're truly "accurate" in terms of what they're marked as I can't say, probably however. Nevertheless it's always been a case of needing something "about that thickness" to fill a gap

I run genuine "Stamvik" - yellow and red packaging. Delivered for $5 from my far eastern friends.. I did the same as you. Ripped them out of their holder. I think they were ~$5 per set delivered. I might have to mic them to see what they measure.

Originally Posted by RayG

Instead of feeler gauges, I use brass shim stock, you can usually buy packets of assorted sizes for $20-30 from the local auto parts places.

This stuff.

One thing I want to try one day is to grind a taper into some spring steel shim, I have heaps of 15 thou and 20 thou spring steel shim, ( I use it for making hand saws) . I'm thinking I'd grind it to taper from 20 thou to 2 thou over 3 or 4 inches. Slice it into strips and use it as wedges to shim up uneven parts. Probably wouldn't work on really wide flat thin parts. Back to double stick tape for those.

I have some of that Champion shim stock. It seems like the only local supply. I did buy some shim stock from China from a seller that has all sorts of tasty treats (search "thin" for the shims or titanium for some treats): http://stores.ebay.com.au/tianmao

I would like to see the work holding for grinding the brass shim stock. I am drawing a blank in terms of how I would hold it outside of wrapping, folding and fastening to a block. But then it would likely spring up in the middle. There has to be a better way?

One thing you might try, on something as long and slender as those parallels, or a new gib. That's to put something compliant between the work and the chuck when you do the first side.

I've used anything up to including that 3mm nitrile rubber you get at Clarke Rubber. Thinner stuff is good also. Its reasonably parallel. But how it works, it spaces the work off the chuck so the pull down is less. But because it squishy, it cradles the work piece, so it does't pull a bend into the work piece onto the chuck, only to spring back latter. It's rubber, its basically touching the work piece, before you turn the magnet on. It will suck down evenly, when you turn on the magnet.

The magnetic pull down is fairly balanced along the length. Your low parts will deflect into the squishy stuff, but the high points are also supported, so they don't pull down nearly as much. Get it right, you will have a dead flat, first side.

Ideally you want it one some thing that has plenty of stock on it. But if you can get your top face flat, while the bottom is cushioned. When you flip it, that straight face doesn't deflect onto the magnet. First ground face goes direct on the magnet.

Takes a bit of experience and some care, as you have less clamping.

For some thing that's close to straight, card stock cut out of Manilla folders works a treat. For some thing really close to straight, strips cut from A4 paper work. If you run a micrometer over A4 paper, 2 sheets in series from a ream. You'd be lucky to measure a difference of 0.01. Yet it will still compress some what. Give it a few minutes wet, if your running coolant, before the grind, if using paper, Rubber doesn't care.

You can get that rubber down to 1 or 1.6mm thick. That still gives you good magnetic attraction, but would put up with a part with a bend of say 0.1 - 0.15mm bend, over the length of that chuck.

At Zenford, where I did my time, we had a stock line of products called Austra. We used to punch out a lot of parallel strips. Up to 1" x 3" x 12" (I still have 3 sets acquired below manufacturing costs). Plus a lot of smaller ones.

They all got loaded up on a big brother to Ueee's Blohm Grinder, 1000 x 600, on a sheet of rubber, for the first qualifying side. Once that's flat, the rest is a walk up start.

Regards Phil.

Originally Posted by variant22

A few months ago I purchased a J&S surface grinder. Since then I have gone a bit grinding mad.

I plan on using this thread to post a few photos of projects that make it onto my grinder. It should also be a place for others to post their grinder projects if they wish..

First up is a tool grinding attachment that I have been building to sharpen Biax blades. Last night I milled two surfaces that were somewhat flat (a quick sanding on a flat surface). I was wanting to make them parallel and to have better finish so I threw the part onto the grinder. 15 minutes later I had this...

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very nice toy to have for sure
congratulation's
Peter