I have been reading through old posts trying to find the answer to a question.
Does anyone know of a jig that will handle the grinding of metal lathe tooling?
The most basic single point cutter requires at least 6 different angles on the faces of a blank of high speed steel.
Traditionally this was done on a high speed grinder by hand. Getting precision angles requires practice, experience and patience. I can do it but I bought my Tormek specifically to help me achieve higher accuracy with the more complex angles.
At a minimum I would need a jig that is adjustable in both the horizontal and vertical along with the angle to the faces of the diamond stone.
Does anyone know of a jig or plans for one.
Rich Colvin posted a sort of platform for this. Don't know if it meets all of your angle needs, but see what you think.
Sharpening Metal Lathe Cutting Tools (https://forum.tormek.com/index.php/topic,3575.msg23029.html#msg23029)
I occasionally have need of this type of grinding and have a couple nice brass protractors like Rich's, but have never gotten to the point of making one.
Rick
I'd love to see Tormek come out with a Goniostat.
Quote from: RichColvin on April 14, 2023, 04:38:45 AMI'd love to see Tormek come out with a Goniostat.
I forgot that you show one and provide information about the Goniostat on your Sharpening Handbook (https://sharpeninghandbook.info/indexJigs.html#Goniostat) site.
I had previously downloaded the drawings for the Goniostat from your site and just looked at them again. I work from drawings like these all the time, and almost always create them for projects that I work on. It would be some work, but is basically straightforward for machining and assembly. I am having difficulty visualizing how this Goniostat is used, however. Do you have any photos or other information showing how it is mounted or setup with a grinding wheel and how it is used?
Rick
Quote from: RickKrung on April 14, 2023, 02:38:09 PMI forgot that you show one and provide information about the Goniostat on your Sharpening Handbook (http://goniostat/) site.
...
https://sharpeninghandbook.info/indexJigs.html#Goniostat
;)
Accu-Finish makes a grinder which uses the side of diamond plates. I'm thinking that something similar to the DBS would work quite well. Instead of holding a drill bit, it would hold the cutting tool. And you would slide the tool's holder left & right to grind the edge.
Quote from: RichColvin on April 14, 2023, 03:30:34 PMAccu-Finish makes a grinder which uses the side of diamond plates. I'm thinking that something similar to the DBS would work quite well. Instead of holding a drill bit, it would hold the cutting tool. And you would slide the tool's holder left & right to grind the edge.
The DBS is an excellent platform for many things like that. I've used it for grinding facets on surfaces of a tool I use for holding strips of bamboo on a mill for planing, in the the early stages of making bamboo fly rods. I posted on this here on this forum, this one using my Viel belt grinder:
Adapting a Tormek Jig (Drill Bit) to a non-Tormek/Sharpening Function (https://forum.tormek.com/index.php/topic,4626.msg33138.html#msg33138)
Here is a photo showing a different fixture for that project. BTW, I abandoned the Viel in favor of grinding on the outer surface of the Tormek wheels. You might recognize the part being modified, these parts having been 3D printed in metal.
DBS-22 Hold Down Grinding Jig 03-06-21 640.jpg
Haven't tried grinding on the side of the wheels, but no reason that couldn't be done.
Rick
Well, I have a mill and a rotary table.
I think I will work on a jig adjustable up to 20 degrees either side, in two axis. The third axis will be to the wheel.
I also have a BGM 100 which I will mount to use the side of the diamond wheel with the same jig.
I have other projects ahead of this so give me a week or two. Photos to follow.
Steve,
If the jig you're making would fit on the slide for the DBS, it would be awesome! I'm thinking it could be only one piece: a holder which rides on the ridge on the Turning Plate (#3 in the parts breakdown). Additional holes may be needed in the Sliding Plate (#2) to give the best angle.
I've just always thought that a new Sliding Plate was needed as the adjustable angle needs to be so wide, as shown on the one I made with a protractor. But maybe, the existing Sliding Plate could be used with a rotating arm added, using the screw (#9) as the pivot point. We'd need some way of marking the plate with degrees. A sticker version of a protractor would work, but having them engraved would be better.
I do not have a DBS as I use a drill doctor for drill bits.
I was not planning on using any of the existing jigs but developing a new, stand-alone jig. Drilling the holes for the slide is the easy part.
I spent part of yesterday doing notebook pencil sketches. Size and weight are the primary factor right now.
I also would prefer engraved degree markings and a rotary table makes those easy.
Progress reports to come as I have them. Right now first project on the lathe are tools for my wife's weaving loom.
The sliding plate, with the angle scale, is flat. To provide a "fresh canvas" on which to mill a radiused slot, engraved angle markings, attach a rotating fence, or whatever, I would add another plate to the top of the sliding plate. Two existing holes in the sliding plate may be usable for attaching this new plate, but more might be better, but no other modifications should be necessary. I've put several holes in mine already for other modifications/enhancements. Ideally, such an added plate would be aluminum, but wood or other materials more easily cut could be used.
Rick
Rick,
While I appreciate the idea I really do not think the DBS will work for what I need.
A lathe tool is ground using compound angles. In all three axis at the same time.
toolbit.jpg
So I would need a surface adjustable in the Y and Z axis with the angle to the stone as the X axis.
Maybe I don't understand the issue, but it seems to me that those facets are not ground all at the same time. In the terms of your diagram, set the side relief with the platform, set the side face cutting angle with the protractor, grind the side cutting side. Change the platform relief angle (if necessary) to the end relief, set the end cutting with the protractor, grind the end angle. In the diagram, most of the the side and end relief angles are the same so the nose radius can be ground last by just rotating on the platform. I'd probably grind the side rake first.
Rick
Rick,
There are 3-5 grinds for these. I noted them in pages like this https://sharpeninghandbook.info/MW-Lathe-Tools-Carbide.html.
Steve,
Interesting thoughts. Looking forward to what you come up with.
Rich
Quote from: RichColvin on April 18, 2023, 05:51:25 AMRick,
There are 3-5 grinds for these. I noted them in pages like this https://sharpeninghandbook.info/MW-Lathe-Tools-Carbide.html.
...snip...
Rich
Yes, my point is that taking into account the vertical angle set by the platform, only one is ground at a time with the tool on the platform, however many there are. It could be said another way: given the vertical relief (platform angle), that two angles are ground at the same time.
Rick
Yep, you are correct.
I am proceeding with my dual angle jig.
While it has been the practice when grinding lathe tooling on a high speed grinder to grind the Back Rake with the tool in the direction shown in fig. 7 -
(https://www.metalartspress.com/sites/default/files/inline-images/sharpening-HSS-lathe-tool-bits-image004.gif)
I prefer to grind the back rake with the tool held longwise to the stone, along the side of the stone. It is more secure, the angle is more accurate, and the grinding process is much safer.
This requires two angles along with the horizontal angle of the tool to the face of the stone. So three angles total.
(https://i.postimg.cc/FKJWSDx6/IMG-2802.jpg)
Here is a jig made by another person that may explain the concept of where I am trying to go.
(https://i.postimg.cc/2S12p2g5/lathe-grinding-jig.jpg)
I sometimes add two more for relief grinds on the sides.
I thought I would post an update.
My goal was to make a metal lathe tool grinding jig that was adjustable for angles in all three axis.
As you have seen in this thread metal lathe tools have been ground successfully on high speed grinders for generations with no problem.
I just wanted a bit more accuracy and buying a low speed grinder is a perfect excuse for making this jig.
Here is an overview.
This is a working "proof of concept" prototype. I still need to clean off all the layout dye, chamfer edges, install the adjustable angle indicators and paint.
This is from above. You can see the left and right tool clamps and the horizontal angle scale.
(https://i.postimg.cc/4yp973tL/IMG-2824.jpg)
Looking from the front you can see the vertical angle scale.
(https://i.postimg.cc/TPPg7fM1/IMG-2817.jpg)
To fit over the rest rod I drilled a hole in some scrap Delron.
(https://i.postimg.cc/q7ZnWS4L/IMG-2823.jpg)
The first step in grinding a metal lathe tool is to create the "Side Cut Angle" The angle for the Side Cut Angle is comprised of two axis. It is ground on the right side of the grinding wheel.
The horizontal scale is set to 10¯ deg°and the vertical is set to 10°.
(https://i.postimg.cc/fLtXsCbh/IMG-2821.jpg)
Second, you grind the "End Cut Angle" This is also two axis with the approach to the face of the wheel being one angle of 12° and the horizontal scale set to 20°. The vertical scale is set to 0°.
This setting gives a 110° single point relief.
(https://i.postimg.cc/wTK56CJ4/IMG-2822.jpg)
Finally the Back and Side Rake Angles are ground. This is done on the left side of the wheel.
This lathe tool is specifically for use on Delron so the Back Rake Angle is set on the Horizontal scale at 26°. The vertical scale is set to 10°.
(https://i.postimg.cc/QxpQVfJ8/IMG-2816.jpg)
Here is a close up of the finished lathe tool.
(https://i.postimg.cc/Cxhq5SK7/IMG-2828.jpg)
Not too bad a cut.
(https://i.postimg.cc/9F4kSH2x/IMG-2829.jpg)
The reason I chose to grind this particular tool first is that my next project has parts made from Delron. Delron requires very sharp edges and larger Back Rake Angles than tools used to cut steel. I thought a Delron cutting tool would be a good first attempt.
I have CBN wheels inbound from Australia and that should be just a bit better than always facing the right and left sides of the standard grinding wheel.
Steve,
That looks very good!