Harold Hall's precision grinding table

[xo18thfa]

Something I’ve always wanted was a better way to grind HHS tooling for the lathe. Research on the internet found a really neat precision grinding table designed and built by Harold Hall. This is Mr Hall’s grinding table:

The table is used in conjunction with a regular bench grinder. The plan for this table is in the “Workshop Practice Series #35, Milling, A Complete Course”

I started one of these and it’s about 1/3 done.

There are a series of attachments for the table. They include a lathe tool grinding, drill bit sharpening, end mill sharpening and others. My main purpose is for lathe tool, but would like to sharpen drill bits too.

It’s turning out very well so far. I think it’s going to do the trick.

 

[tel]

Certainly looks to be coming on well Bob, if my experience of Harold's designs are anything to go by, it will work well. In truth that one is on my 'to do' list.

 

[Maryak]

Bob,

You won't regret it. I made one around 4 years ago. I found a cheap grinder at an Auto shop and all ??? ??? ??? I have to do it fit a safety guard for the wheel and I'm good to go.

Your is looking good.

The Other Bob

 

[steamer]

Looking Great Bob.....Am interested in this...alot of the attachments could find a home on my Baldor Style grinder.......would be nice to sharpen endmills...

Dave

 

[Omnimill]

Looking good! Thanks for posting the pictures - keep em coming.

Vic.

 

[xo18thfa]

Thanks guys. I did a dumb thing and got the wrong size dovetail cutter. So awaiting the right cutter. About 30 years ago I bought a set of drill bits at the original Wal Mart store in Arkansas. They are the best set I've ever had. I would like to bring them back to life with the drill bit attachment.

 

[xo18thfa]

Making progress on the Harold Hall grinding table. I did a boneheaded thing and ordered the wrong size dovetail cutter for the slides. So while waiting for the correct cutter, I got on some other parts.

Basically have the lathe tool grinding accessories done. I am panning to do the drill bit sharpening attachment at some point too.

The adjustment knobs turned out very nice.

The increments were made on the lathe with a “V” held side ways in the tool post. A piece of paper tape with 30 increments wrapped around the lathe chuck. Each increment got three cuts, adding 0.002” depth for each cut. At the end, a very light skim took off the burrs.

The lead screws have 32 threads per inch. Each increment on the adjustment knob is 0.00104” (doing the math).

 

[Maryak]

Good progress Bob :bow:

Mine came to a stop here http://www.homemodelenginemachinist.com/index.php?topic=8511.msg97069#msg97069

Best Regards
Bob

 

[jmshep]

Bob
I made the simpler version of Harold Halls grinding table and the drill sharpening attachment.
They both work well but maybe worth pointing out that the drill jig sharpens them to the four facet configuration. This is good for many drilling operations but not all and I found I could not use it successfully on drills below about 6mm /1/4".

BTW- I would be very proud if my jig was built to the same standard as yours - good luck with it.

John

 

[1hand]

Looks great. Adj knobs are perfect.

Nice job
Matt

 

[xo18thfa]

Thanks men. The correct dovetail cutter arrived and so I am on the sliding parts.

John: I figured it would be difficult to sharpen the smaller size drill bits. I want to save the expensive larger ones if I can.

 

[xo18thfa]

Got all the parts made for the Hall Grinding Table. The sliding table portion is assembled and works great. It was the first time I ever milled dovetails.

I tried to assemble everything and immediately realized those fancy handles are not going to work. They bump into everything and require too much fiddle to make work. I am going to replace them with regular hex bolts and nuts.

 

[JimM]

That's all looking great - fantastic finish to the parts

When cutting the dovetails what sort of depth of cut did you take on each pass and what speed did you run the cutter at

Cheers

 

[John Rudd]

Looking good.....

I bought the material to make one of these, but its on the roundtuit list........

 

[xo18thfa]

John: I know what you mean. This was on the "roundtuit" list a long time.

Jim: I set the cutter to full depth and fed about 0.040" on each pass. Slowest speed on my mill. It chattered a little, but OK. My mill is not very stout. The cutter I got is a poor quality. It seems to be eccentric. All-in-all, it worked, give the dovetails a C+ or B- for a school grade.

 

[tel]

I tried to assemble everything and immediately realized those fancy handles are not going to work. They bump into everything and require too much fiddle to make work. I am going to replace them with regular hex bolts and nuts.

That's something I've always wondered about with the Quorn - they fairly bristle with those handles, which, one would think, would have to get in the way.

It's really looking good tho' - I am almost inspired to start one while I wait for the electronic bits for the EDM.

 

[xo18thfa]

The grinding table itself is done. It's ready to install. The wife gave the "green light" to a new grinder. I found a piece of granite counter top, an oval shape cut out for a sink. Might use it a base for the able and grinder (Thanks for the idea Bob)

I took the handles off and replaced with hex nuts/bolts. The last part in Mr Hall's plan is a "cheater bar" to tighten the handles. May as well just use a wrench then.

 

[xo18thfa]

Finally got the Harold Hall grinding table installed and running. It's nice, I like it. The wheel is all trued up with a diamond point dresser. It runs smooth as a baby's butt. Got all new HSS lathe tools and we are cutting serious steel now.

Also made the drill bit grinding attachment. It works very nice. It cuts a razor sharp 4 facet edge. I have a bloody finger to prove it.

I am glad I did this project. It's a great addition to the shop.

Next up, a Harold Hall dividing head.

 

[Maryak]

You have made a great T&C grinder there :bow: :bow:

Best Regards
Bob

 

[steamer]

Yes you have made a great T&C ! and I too am interested in the dividing head....looking forward to it.

Dave