Grinder Table

Hi,

I need to cut some strips of 6mm MS and have them to a reasonably accurate width, various widths too so it's not easy to simply buy it in...

also I wanted to put a fairly accurate 60 degree angle on some of it, and on some 10mm MS. Three of these needed to be as close to 'spot-on' as I can get it as it's to mate up with 'ways' and 'cross-ways' on the lathe that I'm starting to re-build.

So I looked at making some sort of jig, maybe similar to a router table as used in woodwork.

I had a piece of plate that came off a pallet at work, around 39" x 8" and 5 - 6mm thick. This cut up nicely into two pieces around 12" long to make a base and the remainder, around 18" would make the table. A grinder could be lightly clamped over to one side of the base, and angled so the workpiece missed the guard. I could then twist the grinder to get the angle on the piece.

That was the basic plan and making it up as I went along, I did this...











Initially I had a piece of angle for the work-guide and simply clamped in in place. But then I thought I could do better and came up with a clamp at each end with 13mm bolts. Also a couple of threaded adjusters where I could move the guide by around 0.5 mm at a time to take shavings off the metal with multiple passes.




Three of the angles need to have the concave taken off, not sure yet how to do that, possibly using the sander? Maybe a sander disk on the lathe and a jig bolted to the bed when I get the head-stock built?

I've read about a metal scraper, flat steel with a slightly raised sharp edge apparently, that can take small amounts of metal off but not managed to find one yet as I'm not sure what it's called...

Regards
Peter

A good way of anchoring grinders is by the bolt hole where the side handle screws in. They are M8 on mine and I bolt a flat strip in to anchor them in the Workmate when I'm away from the bench grinder.

Hi,

yes, I can see that working for a 90 degree cut. For an angle it could be a bit tricky getting variable positions...I'm not sure yet how the disk will wear away and the grinder position may need to be adjusted slightly after a few runs.

I'm making this up as I go along :-)

Regards
Peter

How about getting it somewhere close with the disc and then fit a Diamond cup to the grinder to finish off

I did this sorta job for a self built lathe once Peter, I manage to get hold of 4 old large planer blades which were ready angled to make the cross slides then welded 2 of them to the edges of a mild steel plate to mount the tool post on. 1 of the other 2 was welded to the base slide and the other bolted with elongated holes so it could be adjusted, this one was also cross drilled and threaded for grubscrews for the gib strip. The tool post plate edges were finished with a mounted sander similar to the rig that you have made up. I must say that after all my trouble I was a bit disappointed with it as there was too much 'give' with the steel, which allowed movement on the tool post when in use and let the tool vibrate. End result was chatter. However it did for very light cuts. . I thought after that I should have used cast iron plate and maybe had got someone to cut the angles on a milling machine?

Hi,

thanks for the input. I was hoping that 10mm steel would be solid enough. The mating surfaces that I'm making are starting out in 10 x 30mm and if there's any 'play' I'd have thought it would be in the welding.

I've been thinking about this for a few weeks and short of buying one ready made (they do come up on ebay from time to time) this looks like the best option to me.

Fortunately I got a compound slide with the bits that I bought so as long as I can get that mounted solidly it should work.

Regards
Peter

Hi,

Shox Dr said:

How about getting it somewhere close with the disc and then fit a Diamond cup to the grinder to finish off

Click to expand...

I assume it'll be too difficult to use free-hand and keep the face level, and if it's in the rig that I made it'll still leave an indent due to the curve of the disk? A quick search found one on ebay for £100, so that's a none starter, sorry.

Regards
Peter

Are you familiar with the operation of a surface grinder?
Basically like what you've built, except that the grinding wheel is perpandicular to the carriage, and can be dressed flat relative to it. To put the angle on the sides, you'd hold it at that angle and run it under the wheel.

You'd have to do some re-jigging though

Let me know if you need further explanation

Pieces of straight bar clamped at each side to act as stops, whole thing in vice and hand file? You would have the bottoms of the grinding disc groove to help keep you right.

chap, that's what he has. On it's side, all he needs to do is set it at 90*

Hi Pete.

What are you trying to achieve with the strips on the lathe - are you trying to make a compound/cross-slide?

To get the 60-degree andgle with flat sides you need to re-mount the grinder so the plane of the rotating blade is at the angle you wish to grind. This would be easy to do if you using the two threaded holes on the side of the head to mount it so the grinder is pointing tail-end straight up with the wheel parallel to the jig and then have adjustment to vary the angle.

The diamond cup wheel is a good idea but using a stone one rather than diamond. Grinding stel with a diamond wheel will kill the wheel off very quickly. Diamond wheels are for grinding much harder materials like carbide.

Hi,

thanks for all the comments.

Yes it's for a cross-slide, I have the original compound slide to stick on the top.

I can't see any way that I can get the cut or planed surface flat using the grinder, it'll always be 'near'. That's why I'm looking at scraping to finish these pieces off. The write-up that I read said this was the best way to get the surface as flat as required to do the job.

The table is just an exercise in what I could do with a bit of scrap to make a jig that'll get a few pieces made to the same standard/dimensions. I've never seen one before so I made it up as I went along.

Regards
Peter

peter, you can pick them up for a lot less than that. less than 10quid for some. RDG tools sell them and Gloster Tooling

Search for "Diamond Wheel" in Business Office &Industrial

Shox Dr said:

chap, that's what he has. On it's side, all he needs to do is set it at 90*

Click to expand...

Exactly: the trouble is, that the axis of rotation of the disc is at a compound angle in relation to the material movement.
If the face of the disc was parallel to the fixture (ie the spindle perpendicular to it) then the edge of the disc could be dressed true/use a brand new disc, and with an angle jig you could grind as required.

Just an idea.
I can sketch what i mean if my word's arn't very clear.

Hi,

thanks for the explanation, I think I understand, but it sounds quite complicated to do. As it stands my table will do what I need it to for this job.

Regards
Peter

chap said:

Exactly: the trouble is, that the axis of rotation of the disc is at a compound angle in relation to the material movement.
If the face of the disc was parallel to the fixture (ie the spindle perpendicular to it) then the edge of the disc could be dressed true/use a brand new disc, and with an angle jig you could grind as required.

Just an idea.
I can sketch what i mean if my word's arn't very clear.

Click to expand...

1 side of the disc would tend to lift the piece off the table, but with light cuts probably ok.

A cross-slide should really be made from cast iron, you'll rarely see anything like that made from steel. Have you tried looking for parts for the lathe? What type is it?

Hi,

yes, I know, but it'll do until I get one.

It's a Myford ML4, small one. The other lathe that I had was far too big for my workshop and it had to go. Being a Myford, spare parts tend to be over-priced, and being an ML4 there aren't as many spares coming up for it as there are for the ML7, for instance.

This is basically an exercise in what I can achieve when I want to...

I'll be disappointed if it doesn't work but it's hardly life-threatening!

Regards
Peter

Drummond M spares might fit, or be close enough to adapt.

Hi,

yes, thanks, I keep looking but there's not much for weeks and then a few come up together and the prices go too high.

Meanwhile I'm having fun making what I need and learning too.

Regards
Peter