Need a little surface grinding done please...

I have a section of Hiwin linear rail that I would like to have around 1mm removed from the back face. The rail is 310mm long x 15mm wide x 12.5mm deep, its the 12.5 that I need reduced to 11.5. Accuracy is not paramount but the rail needs to be parallel when ground.

I'm located near Worcester so someone local would be ideal but as it would be a small package I could post and arrange collection if necessary.

Any offers of help for a few beer tokens would be appreciated!

Thanks in anticipation, Henry.

Sorry to see that you have had no answers to your grinding problem. I think that the main problem is the amount of metal that needs to be removed, 1mm (40 thou) is a huge amount to remove by grinding in a small workshop. You may have to consider using a professional company.

Brian

What's the material? Milling would be more appropriate unless very hard.

If it is too hard to mill, and you are desperate, you could grind it on the Mill.

Not a nice idea, but I did say desperate.

Turn up an arbor for a thick, depressed centre Angle Grinder disc.

Mount in the mill, cover as much as possible stiff, and very gently grind off your 1 mm, using a lot of passes, and LIGHT cuts.

If the rail is ferrous, place a strong magnet under newspaper or a cloth (Clear so that it doesn't get involved in the rotating parts ) to collect the metallic grinding dust.

Howard

It may be hard but not too hard to yield to a tungsten-carbide cutter - though it might eat a few. I would though ask if machining or grinding one face would induce the rail to warp.

I'd recommend newspaper rather than cloth there, because if something does go wrong and it does "get involved" it is more likely just to tear apart. A piece of cloth whirling around a fast-revolving spindle is best avoided....

[BTW - I remarked once to one of the Mallard Metal Packs stand staff that the blue paper wipes they sell break up easily. He looked a bit worried until I reassured him of the safety advantage - and yes I do keep well clear of moving bits! I did indeed buy a couple more rolls while I was there, too.]

I would also try 'hard' milling if you can do it, I have in a past life done a lot of surface grinding & .040" is a lot to take off & time consuming [costly], a pro shop can do it no problem but they may not want to & it will be expensive.

Tony

Could you machine a 1mm deep slot in the part it, or the slide block bolt to?

Have you checked the hardness of the back of the rail ? Some years ago I was suprised to see these rails being cut to length with a power hacksaw using a normal HSS blade. I picked up an offcut & it was apparent that the heat treatment was only on the very specific areas that the balls contacted - visible by a different texture to the cut around 20 thou wide in the hardened areas - and the rails cut very easily. A file will tell you if the surface is less than pot hard.

Maybe mill the back to within 2-3 thou of finished size & then grind if the required parallelism could not be achieved by milling alone ?

I have a manual Ingar 612 surface grinder that may (just) have the capacity to cover 310mm length - it is nominally 12" table travel and has, I think, a 12" magnetic chuck There are a couple of caveats, though - I have never got around to properly installing or using it since purchase, so don't know how accurate it is. And it is a fully manual machine - my arm would not last taking 40 thou off over the full stroke !

Nigel B.

Wow, thanks for all the replies! To answer them in order:

Brian - I have had a pm from someone who has kindly offered to do the job on their works machine, just the some fine details to sort out.

John - Yes its harder than I would want to mill and possibly wreck an expensive cutter, of course the other problem is holding it securely, even with my 125mm vice it would mean a couple of sets or table clamping the same.

Howard - Yes I'd thought about that but without coolant the workshop will be full of grinding dust, something I wish to avoid. I certainly don't have a magnet strong enough to do what you are suggesting.

Nigel - See my answer to Howard!

Tony - Yes, I'm familiar with hard milling but we're back to the cost of wrecking an expensive cutter and although my SX4 is pretty rigid I'm not sure its ideal for that.

Nicholas - The rail already has a recess, not quite 1mm deep, about 0.8 if I remember rightly, so the job isn't so onerous. Ideally I would make it fit but my problem is that there are some 1mm chamfers on either side and I need a sharp edge to locate off.

So, lets see how we get on, if plan a falls through I'll be back! In fact I'll let you all know how I get on, thanks again...

Henry,

I forgot to say run at low speed to reduce dust flying about.

I DID say desperate. Only had to use that method once.

Like you, I minimise any grinding in the shop, the bench grinder which is as far away as possible from the lathe and the mill. (And that is only used to tidy up the end of the Diamond toolbit )

The cutter grinder is taken outside to be used for other tool or drill grinding.

Anyway, sounds as if you now have the job in hand, so all should end well

Howard