Using Unimat SL as a tool post grinder

[chuckinnc]

I picked up a 7 x10 mini lathe last night to replace the small SL so I am thinking of using the Unimat as a tool post grinder for my 12" lathes, old craftsman & new import. Both have BXA quick change tool post, so I need a idea for mounting the Unimat headstock on a quick change block.
If any one has done this or has good ideas or tips it would be a big help. Photos
would be even better, anyway I need to convert the little SL to something usefull. I could install in on the milling stand and use it as a mini mill but I think
a tool post gringer/drilling head would be more usefull, I am open to any ideas
as how to use the SL for something besides lathe operation.

[Doozer]

What project do you need to do cylindrical grinding for?
Toolpost grinders get grit all over your lathe and it is hard to clean.
With surface grinding, if one knows grinding real well, you can get away without coolant.
With cylindrical grinding coolant is almost a must.
Buy a cylindrical grinder if you need to do cylindrical grinding.
One is on my wish list.
I have a surface grinder, and it will not meet my needs for cylindrical grinding, hence a real one is on my wish list.
I guess in a super pinch situation, a toolpost grinder could be helpful.
But the mess cleanup and fiddling around is not worth it. If you get a project that needs cylindrical grinding, sub it out and pay for it. If rigging this thing up is a novelty, just to say you have capacity to do cylindrical grinding, it might not be worth it. If say you want to grind a 6" long hardened shaft straight in your lathe for example, you are going to have a hell of a time achieving this with no taper. I have used a 5000 pound cylindrical grinder, and getting at dialed in does take a bit of doing. Trying the same thing on a mini lathe, the odds seem stacked against you. Not trying to be a buzz kill, just saying there are a lot of factors involved in cylindrical grinding to get good results. I am only OK at grinding, and wheel selection still blows my mind a little. There are so many grits, bonds, materials, and hardnesses that ones needs to be familiar with for different grinding conditions, it is a lot overwhelming. If you do make this toolpost grinder and get poor results, try not to get discuraged when things start not working out. Investigate rubber-bond wheels as they are more forgiving. That is what swing-grinders use, popular in England. Learn all you can about the different wheels available. Rig up coolant if you can.
--Doozer

[Dawai]

I... well... in the spirit of compadre..

Took a piece of one inch tube, found some 5/8" bushings.. a piece of 5/8" rod shafting.. Mounted a dc motor on the end of it, drilled the end for a 1/4" mandrel. Dc drive from another project.

built a inside tool post grinder.. Less than $20.

What can you do with it? refinish cylinders.. bore.. on the lathe.. polish inside a bore.. I am building a harley cylinder adapter, cut out part to fit a chuck adapter for my L00 chuck mount. Still tinkering with the idea of lateral adjustments to compensate for out of center previous boring jobs..

Most shops just bore it big enough to do away with any set up errors. (egged cylinders). it ain't theirs.. f-it.. time is money.

[chuckinnc]

I don't, not at this time. All my machinist activities are just hobby and never
any critical measurement stuff. Instead of having two mini lathes setting around I was trying to come up with something usefull, not that I need it for anything yet as its just another hobby project. Tool post grinder would just
be a learning tool more than anything.

[vpt]

I have been kind of thinking about doing this same kind of thing. I was looking into getting an atlas 6" headstock machining it just a bit and mounting it to my 10" cross slide swivel. I measured it out and the 6" would be perfectly on horizontal center line of the 10". My thoughts were that I could use the 10" backgeared as a somewhat rotary table and use the 6" to hold endmills, cutters, etc.


I had this thought when I was trying to figure out how to do the recess seen on this QCTP body:

[Mcgyver]

i second the keep the grit away from the lathe sentiment.

besides, you could probably sell that unimat for quite a bit more than a good Dumore tool post grinder will cost....and if the dumore is in good shape, its bearings will be up to the task of grinding which i doubt the unimat's are

[Paul Alciatore]

I have done this. Here is my Unimat on my SB grinding an internal taper.



The Unimat headstock has a piece of 3/8" square stock screwed to it's bottom to allow mounting in my QC tool post. It's location there was chosen to put the spindle axis on the lathe center. The height adjust on the QC tool post easily allows precise centering.

As for results, it did work. I was grinding an ER11 collet holder in the photo and it worked. The finish did show some pattern, probably from vibrations but it is not clear if it was due to the Unimat's bearings or just the overall setup. I can see a lot of room for vibration with all that mass hanging above the SB's compound slide. But the finish was certainly a lot better than a turned finish.

I plan to get some bags filled with lead shot and try them for dampening the vibrations the next time I try something like this.

Also, I did not use coolant and I suspect that it would make a much better finish.

Here's another picuure of the Unimat combined with the SB:



I was milling a flat on a boring bar I was making to bore out a 25mm hole.

And here's another:



This setup allowed drilling a hole in that same boring bar while it was still in the lathe.

I have 60 indexing holes on my SB chuck's backplate so I can easily index drilling or milling operations in the lathe. You can see these indexing holes in the second picture.

In these two photos the Unimat is mounted on the compound slide with a rectangular block I made to replace the original Unimat casting used to mount the head on the vertical post for drilling and milling. I simply added a 1/2" hole through it to allow clamping it down in place of the tool post on the SB. The fact that it is rectangular instead of a casting makes such mounting easy. That block is where I needed to bore the 25mm hole to fit the Unimat's vertical post so it is actually helping to make itself. You can see this partially finished hole toward the back of the block in both pictures that show it.

I find the Unimat is very useful on the SB lathe. And all of these operations were suggested in the original Unimat manual.