A junkyard lathe and mill tool grinder

[vtsteam]

(Note: I recently needed to cut left hand acme threads to complete the boring table for my Craftsman 12" lathe. I found an internal threading tool making thread here on Madmodder, but this led to also wanting to make a tap. The inside tool was produced on the lathe, but the outside tool seemed better made on a grinder. What follows was originally part of the boring table thread, but I've split it off into its own topic here.)

I was hunting around online for a simple sharpening jig for regular lathe tools used for outside thread cutting and came across a really excellent one by Martin Cleeve here:

http://www.gadgetbuilder.com/ThreadingTools.html

Very simple, and so very appealing, to me at least.

Here's my start on it. I found a piece of scrap bracket 3/8" thick and sawed off a piece:

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[vtsteam]

And was able to use my homemade carbide mill to clean it up:

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[vtsteam]

And I used it to clean up all three pieces -- mostly bits of scrap. By this evening, the jig was almost finished. Just a few more tapped holes and couple pins are needed for it to be ready for use.

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[vtsteam]

Little time to work on metal today, but did manage to finish the jig:


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[chipenter]

Been there making tools to make tools and make nothing .

Jeff

[vtsteam]

It get's worse, Jeff:

I remembered I had a  bench sander that I picked up a while ago at a tag sale. Thinking that this might be something I could use with the new jig to grind tools I dug it out.


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[vtsteam]

I knew the belt sander part's table casting was broken. And I already have another belt sander that I use, but I had bought this one for spare parts or another project. A dedicated sharpener seems like a good cause. Here's the broken piece:



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[vtsteam]

I decided I just needed the disk sander part, so I cleaned the motor up, and plugged the sander in -- it worked. I held a little fine sandpaper against the disk to clean it up:


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[vtsteam]

I had an 80 grit sanding disk -- the adhesive was a little old so I sprayed the back with a little 3M 77, let it dry  some and then stuck it on the aluminum disk. I found the guard, but none of the fasteners for it. Luckily they were SAE sizes and I happened to have 1/2" 10-24's for base screws, and even a couple of 1/4" carriage bolts to fit the square holes for table support pivot bolts. Mine were too long as seen in the photo, but a couple minutes with a hack saw and a file and they were shortened to size:


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[vtsteam]

Then I mounted the disk sander table, and put a 1/4" lathe bit blank in my new sharpening jig. It turned out that the original socket head cap screws I  had were too short for this size lathe tool, and I didn't have any longer screws of that type on hand, so I used some round head screws temporarily.

I tried out the new tool grinding jig for position. Pretty clear it wasn't going to work as-is. The rectangular mounting plate that the tool holder sits on interfered with the guard and the disk itself. You can just see it against the guard in the photo. Also the whole jig needed to be moved back further.

I'll make a different table tomorrow to fix the problem.

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[chipenter]

Why make a new table make the jig fit the groove .

Jeff

[PekkaNF]

Can the motor rotate in both directions? Would that circumvent making a new table? If the problem is limited movement on x-axis.

Pekka

[PeterE]

Like Jeff said above, make a new slide that follows the groove. The slide can easily be nearly twice as long as the tabel which will allow for passing over the edges and still be quite stable. Done that you can also add a tool holder that can rotate around a center which will give possibilities for an angular scale of the same type as the Worden tables - see link http://www.hemingwaykits.com/acatalog/Worden_Mk3_Tool___Cutter_Grinder.html.

BR

/Peter

[vtsteam]

Thanks guys! 

I thought about  using the existing table and using a slide, but as Pekka said the problem wasn't just interference , but also the table isn't wide enough to get the tool tip at the periphery of the wheel. The motor isn't reversible I don't think -- at least by me. A slide extension is possible off the table, but I think the action of the wheel will tend to kick it down on the left side, without support.

I could extend the current table, and I think that would work. I might still do that if I don't like my early morning wake up solution, which is to just remove the table and substitute a piece of angle iron bolted to the left side of the guard where the current pivot bolt is located. Very simple. Maybe too simple....

I do think this will allow me to lower the height -- another problem of the Cleve jig I chose to make. The tool tip ends up pretty high. Okay on a larger wheel -- but this one is only 5" -- 125mm. I could abandon the jig if I don't like it -- nothing sacred about it, and the idea of a slide and retaining the old table does still appeal. It's a good one. Well lets just see how the angle iron works out. Not much to it.

Thanks very much for the feedback!  Nice to know a few people are following, and I appreciate all suggestions.

[mattinker]

Following along, maybe a change of title?

Regards, Matthew

[PekkaNF]

The motor isn't reversible I don't think -- at least by me.

Most likely the motor is single phase permanent capacitor run model. Simple addition of single pole changeover switch after power switch should do the trick. Same connection than on "Quorn" TCG book or simple lathe:
http://www.anaheimautomation.com/images/ac/wiring/ACW040%20Wiring%20%28600x344%29.png

But if you don't want to fiddle with electricity, I understand it also pretty well.

[vtsteam]

Thanks Pekka! I'll open up the connection box and check. It would be handy to reverse. No, not afraid to wire it differently.

Thanks again! 

[vtsteam]

I made the side table today out of angle itron, and tried it out. It had a few problems -- it was only 2" wide, and the jig really needed a wider table. I clamped another piece to it to widen it, but on top it was too high, and underneath it was too low. I was able to try grinding a tool, but thought I could do better than this setup.

I decided to try to work with the existing table and the slot -- as suggested earlier by chipenter and others. I think this sander originally had a tiny sliding miter gauge, but that wasn't what I really wanted.

After thinking about it for awhile I found two small pieces of steel -- I needed something thin so the fixture wouldn't end up too high. These were 1/8" thick:

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[vtsteam]

I have a spot welder that I got a couple years ago from Harbor Freight. I don't get to use it very often, but this seemed like an ideal job for it. After cleaning off the two pieces of metal, I welded them together, and milled the narrow strip to fit the slot in the sander's table. It was a little oversize to start with .5" while the slot was .460".


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[vtsteam]

Here's the slide positioned in the slot in the table:

[vtsteam]

I spot welded two more strips of 1/8" x 1/2" to the top side of the slide. These will serve as slide guides for the tool holder, also seen in this photo. I've removed one of the original pieces from  the holder, as it's no longer needed.

[vtsteam]

And here it is in use sharpening an acme threading tool:

[S. Heslop]

Hey this is good. I was just thinking about how i'd grind an acme threading tool a couple days ago.

[vtsteam]

It seems to work well Steve.

The X slide lets me use the whole disk, unlike the original Cleve jig. The Y slide allows me to apply pressure by hand which is a lot more sensitive than a mini leadscrew adjustment (I did consider a fancier version) and has the great advantage that you can pick the small tool holder right up off of the table and dip the tool end in water to cool it while grinding.

The rake of a cut is set by the original pivoting table, and the angle of the tool grind is set in the tool holder and its base/slide.

A paper sanding disk relieves worry about using the side of my regular bench grinder's disk, and I don't have to take shelter from it every time I start it, as normally recommended for a grinder. It will get used frequently as a result.

I'll get some better photographs of the sharpener tomorrow, and the resulting lathe tool -- it was nearly dark when i shot the last two pix.

Of course the slide could have all been milled from the solid -- a 3/8"  (10mm) thick piece of stock would have worked the same. And this could be adapted to just about any disk sander.

[vtsteam]

Here's a test piece of scrap turned with the acme lathe tool sharpened with the new fixture. the threads are pretty good. The tool is a bit too wide at the tip -- so the threads are just a bit narrow at the tip and correspondingly wide at the root, but otherwise I was impressed with the first effort. Just a leetle beet more off the sides of the tool and the tip would be right.

It's difficult to measure the tool tip width without an acme gauge while grinding -- I'll probably end up making something to do a check with.

But very pleased with the first results.