Building Harold Hall's Simple Grinding Rest

[stioc]

Day 10

The build of the rest is finally complete. I wouldn't call this project difficult but it took some time (and dedication) because it does have quite a lot of parts. While I had studied it well before starting and made sure I had tools, supplies etc ahead of time to carry out the project but I realized during the project that a few handy jigs and tools would've helped even more. One of the things I want to make is a better work stop, a AXA holder for the dial indicator (for doing 2nd ops, sometimes you can't avoid this) and add air to the lathe because it works so well on the mill. A vfd on the mill would be sweet...but I need to research what motor will fit my RF30, maybe replace the spindle bearings too.

First task was to true up my 10 yr old grinding wheel which I didn't realize how irregular it was until I did this

This was very dusty work and I should have done it outside. Even with the vacuum on this accumulated on the grinder cart:

Then I attempted to sharpen an endmill...which has a learning curve to understand all the angles and such so that will take some learning and practicing...now that I have the ability to do so in my shop.

 

[ttabbal]

Nice! I'm eyeballing the advanced rest, but it will be a while before I can get to it.

 

[stioc]

The advanced rest looks to be easier to adjust and use so it's a couple of steps above this one for sure. However, I figured it would take me longer to make too. I haven't yet had time to use this one properly but I think this will do ok for my current needs until I decide to get a real tool bit grinder.

 

[pontiac428]

Nice work! That is a lot of parts. The rest looks very functional.

Keep resharpening that end mill. See how it cuts. Repeat. Grind it down to a nub. Once you find the right angles and timing of the flutes (just like a drill bit, only more steps) you'll be able to grind one in your sleep. You might want a good tool grinding wheel (Norton 38A 60-grit) for a better finish and to keep from heating up the HSS. Post up what you grind!

 

[stioc]

Nice work! That is a lot of parts. The rest looks very functional.

Keep resharpening that end mill. See how it cuts. Repeat. Grind it down to a nub. Once you find the right angles and timing of the flutes (just like a drill bit, only more steps) you'll be able to grind one in your sleep. You might want a good tool grinding wheel (Norton 38A 60-grit) for a better finish and to keep from heating up the HSS. Post up what you grind!

Harold's grinding book covers lots of details which prior to making the rest were hard to visualize (I'm a visual person) but I think rereading those will make more sense. I just need more seat time

Thanks for the wheel suggestion! I'm thinking about make an arbor adapter and getting one of those fancy cup wheels...thoughts?

 

[pontiac428]

Thanks for the wheel suggestion! I'm thinking about make an arbor adapter and getting one of those fancy cup wheels...thoughts?

A cup wheel is necessary to grind a flat using proper technique. The dressed surface of a conventional wheel presents a curve to the work. With a cup wheel, you can set up the grinder and rest like a Delta carbide grinder with the rest on the side. A flared wheel will give you an easier time with 4-flute end mills, but aren't great for lathe bits compared to a cup wheel. A bench grinder is made for 6" wheels direct drive, and a tool grinder is made for 4" wheels belt drive, so your surface speed may be slow with the smaller wheel. Cups and flares come in 5", too. You'll have to see what works.

 

[Technical Ted]

Go here for Harold's website. Check the videos... he has them on using the grinding fixtures for grinding end mills and other tools. Lots of stuff on his site:

My metalworking and other interests. Harold Hall

Introduction to my many hobbies and other interests, particularly, metalworking in the home metalworking workshop.

www.homews.co.uk

Ted

 

[HBilly1022]

If you want to sharpen the "ends" of your end mills you should make Howard's end mill sharpener http://homews.co.uk/page121.html. I made one and it works awesome. I've used mine a LOT with very good results. I'm a real HH fan and have made quite a few of his devices and purchased all of his machining books.

 

[stioc]

So the other day I decided to give the grinding rest a try using a wood chisel as my test subject. The end on it is pretty well chewed up and rough.

I started by getting the end nice and square and that worked better than I expected

Next I set the angle using a 30deg angle block against the fence. The idea is to maintain the angle and feed the chisel straight while also keeping contact with the side of the wheel. One of those moments you need a third and a fourth hand.

The results were ok but not great, one end of the edge was sharper than the other. I didn't take a pic. However, despite my wishful thinking that I was done with the rest this made it pretty obvious to me that in order to take advantage of this rest I really need to make a couple of accessories for it also.

So, I started with the swivel plate because it forms the basis for several other tool holder accessories.

 

[pontiac428]

Time to get yourself a cup wheel. Dressed surfaces do so much better than the sides of a standard wheel. Set up that rest to work like this pic, and you've really got something: