# Lathe Tool Grinding Jig (no Fb)



## Andre (Jun 26, 2015)

Always took too long to grind threading tools, the wheel guard on my cheap grinder is plastic so the tool rest is flimsy as all get-out. So I made this  Not as fancy as some I've seen, but I don't have tons of time either.

Eventually I will engrave a scale on the back to set accurate angles, and I still have to build a clamp.

It has a 7* relief built into it, maybe on another side I will add a 10* bevel because when you tilt it the angle seems to minimize.













Tool Bit Grinding Jig 2



__ Andre
__ Jun 26, 2015


















Tool Bit Grinding Jig 1



__ Andre
__ Jun 26, 2015






Thanks for looking!

Andre,


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## Ed ke6bnl (Jun 26, 2015)

for some reason I am unable to load images.


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## Andre (Jun 26, 2015)

Ed, maybe you can see them here:

http://www.hobby-machinist.com/gallery/albums/tool-grinding-jigs.408/


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## Hex173t (Jun 26, 2015)

I'm having no luck seeing them either.


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## Andre (Jun 26, 2015)

I know for a fact that the pictures in the Media section are set to "Public". Here they are in link form.







http://imgur.com/9qxAkLs,YHkbart#0


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## Inflight (Jun 26, 2015)

I can see the images in this thread, and the fixture is very useful looking. I'll be making one of those this week.


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## Mark_f (Jun 26, 2015)

i can see the images also......good job Andre.


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## kvt (Jun 26, 2015)

Images are there in both places and that looks good.   I need to build something,   I cannot hold anything steady enough to get a good edge on it by hand.   Good work,


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## Andre (Jun 26, 2015)

InFlight, some dimensions if you'd like to make one yourself.

Aluminum bit: 1.1" round at widest point, 5/8" shank with small relief in the middle for 1/4-20 (dog point) set screw. So it clamp in the relief without raising a burr, making it lock up.

Steel frame: 1 1/8" mild steel, 5/8" bore, with a 7* relief on the bottom. Set screw is recessed below the top surface so it can be flipped for neural relief. 

This was surface ground on four sides, but as long as the front face is faced in the sae setup as it's bring bored in the lathe you should be fine.


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## Inflight (Jun 28, 2015)

I had a little time in the shop so I started my version of the grinding fixture. I made it from whatever material I found in the scrap bin.  The steel base is surface ground on all sides and I graduated the aluminum cylinder with 360 lines. I still need to make a clamp and add threaded clamp holes. 




Matt


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## Mark_f (Jun 28, 2015)

Inflight said:


> I had a little time in the shop so I started my version of the grinding fixture. I made it from whatever material I found in the scrap bin.  The steel base is surface ground on all sides and I graduated the aluminum cylinder with 360 lines. I still need to make a clamp and add threaded clamp holes.
> 
> View attachment 106432
> 
> ...




Great improvement. I like the graduations. This would be great to use on the belt sander to touch up tools and especially to sharpen the tangential tool bit.


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## Andre (Jun 28, 2015)

You outbuilt me! 

Very nice work! I might graduate mine in the same way


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## Inflight (Jun 28, 2015)

It's not a competition , I just wanted an excuse to run the surface grinder.

I will say that the graduations were the toughest and most time consuming part of the project.

Thanks for the inspiration!


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## Inflight (Jul 2, 2015)

Quick update here.  The grinding jig is working very well but for single point threading tools, it does not provide for the helix angle of the thread. To remedy this, I mounted the holder in a small grinding vise at the appropriate helix angle.  My tests of before and after show me that even a small amount of clearance is critical to smooth threads.  




Matt


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## Andre (Jul 2, 2015)

You mean it's not cutting a relief after the edge? I made my jig with a 7 degree angled bottom, to automatically give me relief.


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## Inflight (Jul 2, 2015)

I have the 7 degree relief, but I'm talking about rake angle (aka, helix angle). Not such an issue with sharp vee threads, but for Acme or square threads, and especially multi-start threads, it's of critical importance.  Check Machinery's Handbook or another good text for proper description and geometry.


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## chip maker (Sep 11, 2015)

How and  what did you use to put the graduations in with ? I've made a few tooling items but can't seem to get a good way to do the graduations on them. I have tried a Dremal bit but wasn't strong and broke. Tried just a steel pointed bit but that didn't seem to work. Maybe I'm just not going at it right. Looks like this holder is for sure on my to do list and will be starting it shortly.


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## Inflight (Sep 11, 2015)

Chip Maker said:


> How and  what did you use to put the graduations in with ? I've made a few tooling items but can't seem to get a good way to do the graduations on them. I have tried a Dremal bit but wasn't strong and broke. Tried just a steel pointed bit but that didn't seem to work. Maybe I'm just not going at it right. Looks like this holder is for sure on my to do list and will be starting it shortly.



The engraving tool I used was made from the shank of a damaged solid carbide 1/8" endmill. I ground the tip to a cone, then ground a flat across the diameter.  With this tool locked (not spinning) in a collet, I dragged the point into the work until the depth looked OK.  The work was held in a 5C collet Spin-Index jig allowing the 360 graduation.


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