# Harold Hall Mill Bit Sharpener



## YotaBota (Mar 29, 2020)

It Works!!!!.
Here is a link to the instructions and prints, http://homews.co.uk/page121.html
It worked out pretty well, I changed the measurements to imperial (ish) and used what material I had on hand. The M4 and M5 were changed to 10-32 and I used 5/16 NC bolts instead of the M6 stated. Where it called for a 1/4 -40 thread I just used a 1/4 -28 since I don't have a 40 thread tap. The body was drilled using 1/4, 11/32 and 1/2 inch and then the stop was machined to fit the body. For the PIN, I didn't like the idea of riveting so I used a shouldered 4-40 screw, threaded the stop to match, cut the shoulder about a 1/2 inch long then used LockTite to hold the pin in the body. Now there is no chance of the "rivet" coming loose and it still lined up well with the body.
A word of caution - when you touch the mill bit to the wheel it only takes a half a second for the end of the bit to turn blue, you need to use short touches and low pressure against the wheel.
I'm going to call this one done, now onto the carriage stop.


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## YYCHM (Mar 29, 2020)

NICE!!!! You going to offering a sharpening service now?  I have a dozen or so EMs that need some TLC.

Craig


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## YotaBota (Mar 29, 2020)

I think I'll pass on the sharpening service, I have enough of my own bits to sharpen. Your wobbler turned out well, this should be a breeze for you to put together.


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## YYCHM (Mar 29, 2020)

Ya, I've been eye balling that very same jig you built for quite some time now.  Time to get her done I think.


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## YYCHM (Apr 1, 2020)

Well..... you inspired me to get her started.






Made the 1/2" tool holder today.  Tomorrow I'll tackle the body and stop.

Cheers,

Craig


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## Tom Kitta (Apr 1, 2020)

Yeah I should start thinking of making some endmills sharper I own a TC&G and I have one of these air bearing gizmos - should at least get it all working. For sharpening the front only I also have a little fixture that takes 5C collets so I can do bigger stuff (air bearing maxes at 5/8).


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## YotaBota (Apr 2, 2020)

You did the easy part first. Amazon delivered me a new set of 3/8 bits so I need to make a holder for them, sounds like today's project.


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## Brian H (Apr 3, 2020)

YotaBota said:


> It Works!!!!.
> Here is a link to the instructions and prints, http://homews.co.uk/page121.html
> It worked out pretty well, I changed the measurements to imperial (ish) and used what material I had on hand. The M4 and M5 were changed to 10-32 and I used 5/16 NC bolts instead of the M6 stated. Where it called for a 1/4 -40 thread I just used a 1/4 -28 since I don't have a 40 thread tap. The body was drilled using 1/4, 11/32 and 1/2 inch and then the stop was machined to fit the body. For the PIN, I didn't like the idea of riveting so I used a shouldered 4-40 screw, threaded the stop to match, cut the shoulder about a 1/2 inch long then used LockTite to hold the pin in the body. Now there is no chance of the "rivet" coming loose and it still lined up well with the body.
> A word of caution - when you touch the mill bit to the wheel it only takes a half a second for the end of the bit to turn blue, you need to use short touches and low pressure against the wheel.
> I'm going to call this one done, now onto the carriage stop.



That is an awesome little project. Nice Job!
Now I have another tool to make...and I thought I was getting caught up with my "things to do" list...LOL


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## Brian H (Apr 3, 2020)

YYCHobbyMachinist said:


> Well..... you inspired me to get her started.
> 
> View attachment 8372
> 
> ...



Nice!
Hey, did you make the vise on your mill? I like it! I have been looking at some "compact" 3-4" vises, but, they don't fit in my budget. It's tough to get good tooling for the small mills


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## Crosche (Apr 3, 2020)

Nicely done!


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## YYCHM (Apr 3, 2020)

Brian H said:


> Nice!
> Hey, did you make the vise on your mill? I like it! I have been looking at some "compact" 3-4" vises, but, they don't fit in my budget. It's tough to get good tooling for the small mills



Didn't make it, it came from BB.  It's ok, but very limited as to what it can hold.

https://www.busybeetools.com/products/milling-vise-low-profile-1-7-8in.html

What are you using now?


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## Brian H (Apr 3, 2020)

YYCHobbyMachinist said:


> Didn't make it, it came from BB.  It's ok, but very limited as to what it can hold.
> 
> https://www.busybeetools.com/products/milling-vise-low-profile-1-7-8in.html
> 
> What are you using now?



I got this one on Amazon for $120. Its really sturdy and accurate, but a bit awkward due to its size.


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## YYCHM (Apr 3, 2020)

Brian H said:


> I got this one on Amazon for $120. Its really sturdy and accurate, but a bit awkward due to its size.




YIKES  And I thought my 4" soba overwhelmed my mill, that's crazy.


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## YYCHM (Apr 3, 2020)

Well..... Busy Bee in Calgary is closed until further notice.  Now I'm really motivated to get this jig up and running.

I've discovered a SNAFU with the design.  It doesn't accommodate ends mills 1" and larger


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## Tom Kitta (Apr 3, 2020)

I had same vise on my mini mill like 4 years ago or 5. It was a bit ... big. I used it later on as a drill press vise - not very precise - got it from KMS & sold it few months ago.


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## YYCHM (Apr 4, 2020)

Progress.  Tool holder, body, stop and feed screw (1/4 X 20)

I hate metric plans, they just send me into a dither on how to sub metric to imperial.

This post is actually 3 days older than time tagged. Guess I never saved?


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## YYCHM (Apr 4, 2020)

First brain fart of the project.....






That pin was supposed to follow the stop!!!  Couldn't figure out why the plans called for riveting the pin?????  Rivet it to what?  Now I get it LOL.  Oh well, will be making another stop when my 1/4X40 tap arrives.






Can't proceed with the table until I figure out how it's going to mount on my bench grinder.  That factory table bracket is a problem, it's riveted on!!


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## Brian H (Apr 5, 2020)

YYCHobbyMachinist said:


> First brain fart of the project.....
> 
> View attachment 8451
> 
> ...



That looks pretty nice.
(It would appear we shop at the same store...PA blue...LOL)
I have seen a couple youtubers that have made full width tables for their bench grinders would that be an advantage here? Do you have to adjust the height for each diam. of cutter? I read through the webpage and I was confused about a couple parts.


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## YotaBota (Apr 5, 2020)

In theory I don't think it should matter if the pin is attached to the stop or the body, as long as the stop slides freely. 
For the mounting bracket if you drill out the rivets, is there room between the guard and the wheel to allow bolting the bracket back on? If that works then drill the new support bracket to match the holes in the guard and carry on.
So far so good.


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## YYCHM (Apr 5, 2020)

Brian H said:


> That looks pretty nice.
> (It would appear we shop at the same store...PA blue...LOL)
> I have seen a couple youtubers that have made full width tables for their bench grinders would that be an advantage here? Do you have to adjust the height for each diam. of cutter? I read through the webpage and I was confused about a couple parts.



No height adjustments required once it's set up.  Which parts are you finding confusing?

Craig


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## YYCHM (Apr 5, 2020)

YotaBota said:


> In theory I don't think it should matter if the pin is attached to the stop or the body, as long as the stop slides freely.
> For the mounting bracket if you drill out the rivets, is there room between the guard and the wheel to allow bolting the bracket back on? If that works then drill the new support bracket to match the holes in the guard and carry on.
> So far so good.



I've been considering removing the mounting bracket and replacing it but the amount of lateral flex in the guard has me concerned, it's pretty flimsy.  That factory mounting bracket is held by a single rivet BTB.  How solid laterally is your setup?


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## YYCHM (Apr 5, 2020)

Well..... this is turning into a bit of a gong show.  That factory mounting bracket has to come off my grinder regardless of how I mount the jig table.






Not only is it riveted on, it's spot welded to boot.  Thank you Powerfist

Time to dig out the Dremel I guess.


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## Brian H (Apr 5, 2020)

YYCHobbyMachinist said:


> Well..... this is turning into a bit of a gong show.  That factory mounting bracket has to come off my grinder regardless of how I mount the jig table.
> 
> View attachment 8461
> 
> ...



Working on top dollar "Chinesium" is fun.....right????....LOL


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## Brian H (Apr 5, 2020)

YYCHobbyMachinist said:


> No height adjustments required once it's set up.  Which parts are you finding confusing?
> 
> Craig


I am not clear on the function of the two pieces. Are they attached or is one piece basically a guide/stop for the movement of the end mill holder? What is the purpose of the 4 holes? I need to re-read the article again.


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## YYCHM (Apr 5, 2020)

Brian H said:


> I am not clear on the function of the two pieces. Are they attached or is one piece basically a guide/stop for the movement of the end mill holder? What is the purpose of the 4 holes? I need to re-read the article again.



The body with stop are bolted to the table.  The tool holder simply slides along the body with the stop dictating depth of tool plunge.   With the stop retracted the 4 holes allows the body/stop to be positioned such that the end mill mounted in the tool holder is just shy of touching the grinder wheel.  With every thing set up you now advance the stop towards the grinder wheel using the feed screw which is 0.001" approx.  (for a 40 TPI feed screw) per hash mark on dial. 

Does that make sense now?


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## Brian H (Apr 5, 2020)

YYCHobbyMachinist said:


> The body with stop are bolted to the table.  The tool holder simply slides along the body with the stop dictating depth of tool plunge.   With the stop retracted the 4 holes allows the body/stop to be positioned such that the end mill mounted in the tool holder is just shy of touching the grinder wheel.  With every thing set up you now advance the stop towards the grinder wheel using the feed screw which is 0.001" approx.  (for a 40 TPI feed screw) per hash mark on dial.
> 
> Does that make sense now?



Yes. Thanks for the explanation.


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## YYCHM (Apr 6, 2020)

@YotaBota What size is your bench grinder?






The only way I can make this work is to fir the rest out a good 5/8" from the support bracket.  Starting to look like I'll have to build a wood base to make this all come together


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## YotaBota (Apr 6, 2020)

Mine is a 6" Delta Shopmaster, the tables bolt on. The guard isn't very stiff either but then there isn't a lot of pressure needed so it doesn't move around at all. What about a support that is long enough to use a bolt at the front of the guard and a bolt an inch or two back. The bolts on mine are horizontally about an inch apart ( shows in the first pic I posted) and that stiffens it up quite a bit more than the bolts being vertical. I used 1/4 x 1 1/2 for my support and it worked out well.
Lee Valley has nice stand that mounts to the table if you need ideas.


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## YYCHM (Apr 7, 2020)

Well...… I impressed, this thing actually does work!
















A re-sharpened 1/2" 2 Flt cut like a champ.  I don't retire end mills until they are crying uncle so I know this has been a success.


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## YotaBota (Apr 7, 2020)

Gotta love it when plans actually work, now you can buy more tools with the money saved not buying new bits.


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## Bofobo (Apr 13, 2020)

Could you, if still needed, just make a bracket from the base of the grinder for added stability?


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