Basic Harold Hall Rest movement

I am about two thirds completed with the basic grinding rest of Harold Hall.

I noticed, as designed, the table have almost unlimited in tilt forward and backwards, but very limited to left and right.

With a few small changes to the bottom half of the design, it will be able to tilt just as must to the left and the right as forward and backwards.

Is it really essential to be able to tilt left and right much?

I am going to implement one of the two changes, as I feel it will make my life easier. The other one depends on the answer.

I will show my mods with a pic or two when completed.

Hi Johan....

I have also made Harold Halls grinding rest and I too wondered what the left & right tilt was used for, but I had made it by then !.... after much head scratching I couldn't understand what use it would be and it wasn't until I saw a Quorn in action that I realised it did have a function and was a necessary item.

The tilt can be used to 'wipe' a cutting tool over the grinding wheel in order to limit the striations that a stationary grind would create, you need to set the top of the rest parallell with the wheel for this, unfortunately since I found this little operation was available to me I have not had chance to try it out as yet.!

Here is my rendition of H.H's grinding rest mounted on an old lathe bed...I must say the rest works great.

rgds...Bob.

Hi Johan again... I should have inserted that it can have a function other than setting the top table rest horizontal.

...Bob.

If you haven't already looked at Harold's web pages it is probably worth seeing his updates to the original design.

Harold Hall's workshop

Martin C

I have just ordered the metal to make HH simple rest from MEW issue 109 pg 17. I had not heard of it till recently and had been putting off making the advanced one.

I would be interested in any hints and tips for the construction. In particular if anyone has a simple way to use a vertical mill to cut the 30 degree sides on the slides.

They are too long to fit in my vice length wise, and i don't have a tilting table. I do have two angle plates, all I can think of is bolting them together to give a 30 degree face.

Adrian

Thanks Martin for giving H.H's updates to original design.

Adrian, as you can see I haven't followed H.H's design but used what bits I had in my junk box, the actual rest table and fittings sit on an old rotary milling fixture and this forms the 'slide' bit of the design, it works just as well.

I don't think you need to get the dovetail angles to exactly 30 degrees I should imagine any nearby angle will be ok so long as they are the same angle... in fact if I was making it, I would make the female part out of 3 pieces and screw them together, it saves having to have the right dovetail cutter and is not a part that needs to made for heavy work...the same goes for the male part of the slide.... is anyone going to inspect it afterwards?

You can even make the parts so that if the screw holes a elongated a bit you wouldn't have to have gib strips...nb..I am definately not a purist!

....rgds..Bob.

Harold touches on this on p54 of "Milling, a complete course" during the construction of the boring head (grinding rest is also in book). Basically, if you ensure the ends of the block are dead square to the length, clamp it end-on to an angle plate such that it's on a 30deg angle, with enough sticking proud of the plate that you can make a clean pass out the end. Then mill down until the inboard edge is down below the plane of the horizontal bearing surface. Hope this is clear enough.

Having made Harold's simple grinding rest a few year ago now I am at a loss to why the question from Johan. The tilt gives the necessary tool angle and the fine adjustments the tool advance. Both covering all that is necessary.

The only drawback to this original design is that the single screw fixing the table to the ball does, if one is not careful, allow the table to rotate.

The only other complaint re the simple rest is;- Having made Harold's milling edge and end sharpening holder it puts the end of the mill too high and the simple grinding rest doesn't go low enough.

This means I will have to raise the actual grinder DOH!!!

Bob. It sounds as if you have never watched Harold's video's

Edited By David Caunt on 19/04/2020 14:29:42