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+--- Thread: Lathe Tool Grinding Helper (/thread-3734.html)
Lathe Tool Grinding Helper - randyc - 10-16-2017
Another primitive tool from which it can be deduced that I have very low standards
I used to freehand-grind lathe tools but that’s no longer practical because my hands have become very shaky. So I made something that helps maintain consistent angles when grinding cutting tools.
Below is a 3/16 thick steel table with a couple of brackets welded on the underside (HAZ is visible in the photo) that bolt it to the grinder where the tool rests formerly mounted. The table can be adjusted for angularity but not for the individual wheels (the green wheel on the right is for carbide, of course),
Note that this Rube Goldberg sharpening device was not designed, it sort of took shape as I pulled out discards from the scrap pile. I doubt that the entire project took more than ninety minutes and a do-over would result in something considerably different.
[attachment=15166]
Next was making a sliding tool holder, shown below. The idea was to pass a HSS tool back and forth against the grinding wheel, held at a constant angle until the required shape was obtained. The process ideally would be repeatable so that minimal time would be required for re-sharpening.
The steel arm pivots at the point where the black knob is located . The little knurled knob attached to the arm is turned to a small diameter at the far end. The entire piece is captured and spring loaded. Lifting the knob retracts the locating "pin" and the arm can then be rotated freely.
Releasing the knurled knob allows the pin to drop into one of the holes in the sliding holder. Note the tack welded steel strip at the bottom of the tool holder plate. The purpose of the strip is to guide the tool holder repeatably along the steel grinding table.
[attachment=15167]
The tack welds discolored the HAZ so I heated the whole plate with a torch to produce the blue color. Just because.
[attachment=15168]
In the above photo, the arm has been adjusted to an angle forty-five degrees from vertical. In the photo below, a HSS blank has been secured to the arm with a small C-clamp. (The blank would be clamped on the other side of the arm when using the green wheel.)
The guiding strip is at the rear of the tool holder so that the holder is pushed away from the grinding wheel not into the grinding wheel if the HSS tool is fed too agessively.
[attachment=15169]
Sliding the tool holder plate back and forth along the table, shapes the desired angle (using the two knobs of course). At first, the sliding tool holder doesn’t even contact the table at the rear and the angle of the holder is simply adjusted by eye as the holder is moved. As material is removed from the HSS blank, the sliding tool holder gradually comes into contact with the table.
After the preliminary roughing is complete, the clamp is loosened, the tool moved forward very, very slightly and then re-clamped. The same back-and-forth process is used but at this point, only a small amount of material needs to be removed to obtain the finish shape.
At this point, the cutting tool is removed and carefully lapped with carbide paper taped to a pane of glass. The lapping process is mandatory for best surface finishes - even single-pointed threads have a nice finish, like the piece below.
[attachment=15171]
I keep meaning to make a bracket to attach a vacuum hose on the underside of the grinding table. In the meantime, I manually clear grit from the table and the sliding tool holder often.
This contraption is mounted on a rolling table that includes a belt/disc sander and a knife sharpening sander. (There is a shop vac parked under the table top connected to the belt/disc sander.) I keep the “dirty” operations together and, if necessary, even roll the whole thing outside for operation if grit becomes an issue in the shop.
BTW I don’t like to dunk the cutting tool in water and in this case it would be a real PITA – the entire holder would have to be dunked or the tool unclamped and removed ! I prefer to use compressed air for cooling. It works fine and doesn’t stress the tool as much as suddenly dipping in water.
The three (sometimes only two) angled cutting faces are produced by rotating the blank in the fixture and re-setting the angle. In order to obtain a compound angle, I place a small object underneath one edge of the sliding table, whatever fits conveniently and can be secured.
In this case, a small “bulldog” clip is used – scraps of material, even cardboard can be packed under the sliding table and secured by the clip to increase the angle by lifting the sliding holder.
[attachment=15170]
Hey, I said it wasn’t designed, right, I just cobbled the thing together. If I’d spent time thinking about it, I would have included a more practical means of angular adjustment, ha-ha-ha. I also would have made two independently adjustable tables.
RE: Lathe Tool Grinding Helper - pepi - 10-17-2017
I like it, covers all the bases.... the bull dog clip, .......... to fine trun the angle ;-) Got to say sometimes simple engineering, down and dirty work great.... to many over complicate things.
Thanks for the write up, if I ever get good enough to grind cutting tools, this is one to remember.
Cheers,
Greg
RE: Lathe Tool Grinding Helper - randyc - 10-17-2017
Bad, bad memory retention ...
About three years ago - this was after I'd built the grinding fixture described above - I decided to start a do-over. I had completely forgotten this until tonight when something I was reading jiggled my memory ! I had ordered the following parts:
[attachment=15177]
Diamond cup wheel + 3000 RPM motor or so it says on the nameplate. (It took a few minutes to find them in my highly disorganized shop.)
The idea was to have a grinder that would accommodate any lathe tool, HSS or carbide, and maybe a few other types of cutting tools as well. But due to family health issues at the time, I never got around to this project. This time, if I can suppress my impulsiveness, I may take a shot at actually designing the thing, ha-ha-ha.
I hope to add a follow-up to this post in the near future.
RE: Lathe Tool Grinding Helper - randyc - 10-19-2017
A tool grinder must have the capability to adjust to any compound angle, right ? For commercial tool grinders (mucho thousands of $$$) this is accomplished by a series of precision slides, adjustable to various angles, the capability to rotate in three dimensions and so forth.
It hit me that a camera tripod head is adjustable to any compound angle, like a tool grinder, albeit without the capability of pre-setting to fixed angles and the precision slides and stops.
This is a sketch of my hillbilly grinder concept. I've ordered a chinese tripod head from eBay for $6 to check the concept and if it looks practical, I'll buy a good head (like the one on my French-made Gitzo tripod).
At the far left of the sketch is the motor and cup wheel. The sliding tool holder is not shown in the sketch but it will probably be something similar to the one I already use. (I can't figure out how to enlarge this sketch unfortunately.)
[attachment=15185]
The head can be adjusted to any reasonable angle, it can be raised and lowered, rotated, moved forward and backward to accommodate a work envelope of about 4 x 4 inches. If this works, and with the proper collet or vee-block system, maybe I'll even be able to sharpen end mills.
The cost of this thing should be small, I think that I have less than $100 into the wheel and the motor. The rest, except for the tripod head, is just fabrication. Whaddayathink, any suggestions ?
P.S. Obviously this concept would be a light (lighter, lightest ...) duty machine. I envision roughing on the system I already have and making the finish passes on this thing. With a solid head like the Gitzo and careful, light work, I think that this might work fairly well.
RE: Lathe Tool Grinding Helper - EdK - 10-20-2017
With a good quality ball head it should work fine for light finishing work.
Although good ball heads are not cheap.
Ed
RE: Lathe Tool Grinding Helper - randyc - 10-20-2017
Yep, a basic Gitzo head is over $300 (tripod not included).
Shocking Surprise - randyc - 10-20-2017
I wrote yesterday that I'd placed an order for a $6 ball head, to be used as sort of a "mock-up" for determining dimensions and feasibility. My bad - I don't know where I came up with $6, the actual cost was about $25. No big deal.
Thirty minutes ago, it was on my front porch !!! 24 hours from ordering to receiving - for a $25 part with free shipping - I am impressed.
OK, next: This thing is QUALITY, bottom to top. It's larger than my Gitzo head and weighs three or four times more (of course, since Gitzo uses titanium for its ball heads) but for my purposes, heavier is better. Check it out:
[attachment=15186]
The country of origin is sort of mystical, there is no "Made In XXX' on the head or in the pamphlet that accompanied it. It is noted that the product is distributed by a Nevada company solely for Amazon. For $25, it can only have been manufactured by a company that is now bankrupt or by someone who speaks Mandarin, Korean, etc. The pamphlet is well-written incidentally.
The head has a detachable mount for a camera base which is impressive in itself since it is held in vee-ways secured by a large dual-spring-loaded clamping knob. (I can easily visualize the toolholder base held there.) The head has two different levels, a standard spirit level and a round bubble level. The entire head pans 360 degrees and can be clamped at any point, of course. BTW, the only plastic parts in the device are the knobs and the spirit and bubble levels.
But now the really good, completely unexpected, news. The ball joint is secured by TWO clamping knobs - I've never seen this in a tripod head in years of photographic experience. I am delighted by the extra security of course and am now pretty sure that the $300 Gitzo head may not be required for my purpose.
After all, it the concept is a flop, I'd have a $300 head to be Craigslist-ed or eBay-ed. (Since I already have a Gitzo tripod there's no need for another one.) If I face-plant, I'm into the project for less than $100, some material and my worthless time.
[attachment=15187]
Now to get off my lazy butt and maybe make a wooden mock-up before making chips -
RE: Lathe Tool Grinding Helper - Dr Stan - 10-20-2017
Just keep in mind you have a safety nazi watching over your head.
RE: Lathe Tool Grinding Helper - EdK - 10-20-2017
(10-20-2017, 08:11 PM)randyc Wrote: I've never seen this in a tripod head in years of photographic experience.My FLM ball head has that feature but it cost a whole lot more than $25. But it does have a proven track record.
You should be fine with that one though considering what you'll be using it for.
Ed
RE: Lathe Tool Grinding Helper - randyc - 10-20-2017
(10-20-2017, 08:55 PM)EdK Wrote:(10-20-2017, 08:11 PM)randyc Wrote: I've never seen this in a tripod head in years of photographic experience.My FLM ball head has that feature but it cost a whole lot more than $25. But it does have a proven track record.
You should be fine with that one though considering what you'll be using it for.
Ed
Ed,
Any chance of getting a model number for your head (the metal one, LOL) ? It would be good to have another backup along with the Gitzo if this thing doesn't work. This one does lock up nice and tight so it's unlikely that a more expensive head will be required but JIC ... with wear the mechanism may not be as secure as it is now.
(BTW, what is the purpose of two locking mechanisms, do you know ? Seems like overkill for photography, even with a long telephoto lens. Not that I'm complaining, ha-ha-ha.)
Cheers,
randyc
P.S. A thought: maybe locking one knob lightly allows a fairly precise adjustment which can then be maintained by locking the other knob ?