Order of things

David S said:
First for your lathe the thinner the parting tool the better. Like I mentioned, mine is 0.040" wide and I have one that is thinner that I ground from a HSS blank lathe tool.

In the absence of a set of reamers I would drill the hole in the knob first and then do the final turning of the threaded piece so that you can get a slight interference fit to the knob or alternately use loctite.

David
Click to expand...

I have to agree. I use a .040 parting on my MaxiMat7 and on my Sherline. On my watchmaker's lathe I have an exacto blade ground as a parting tool which is presented upside down. Most of my machining is for clock repair.
 
Maplehead,

When I started I had a Unimat db200. With a 1/10 hp motor I assume it has similar power to yours, although the unimat did have many reduction options.

I am showing some pics of the parting tools that I used for my small lathes
parting tools.jpg

The left tool was the parting tool that came with the Unimat..about 0.100" wide. The centre one is the one that I ground to work with the Unimat tool holder and is 0.040" wide, and the far right is the 0.040" wide parting tool for my Atlas 618.

I strongly suggest that you make a thinner parting tool for better performance.

David
 
On the topic of cut off tools. I built a holder that holds a .032 piece of bandsaw blade.
I always have a dull bandsaw blade and one bandsaw blade makes a lot of cut off blades.
My largest bandsaw takes a .032 x 3/4 x 9' 11".
I don't use a bandsaw tooth. I just grind it like a cut off tool. Then heat and quench the end so it is hard.
I cut the slot for the holder with my little bandsaw that takes a .025 blade. I makes a good fitting slot for the .032 blade.
 
I picked up some 1/8" brass rod today.
One approach I can take is to just turn it all down to .109" and then thread one end to an inch in length threaded. Sounds so much faster and easier.
However, I like that interference fit idea for the 3/8" wide thumb wheel.
So my question is, how much over the .109" should I make the section where the thumb wheel will rest?
I'll be using drill bits for the thumb wheel center hole. My choices are limited. 7/64" or 1/8".
Should I use a 7/64" drill bit and leave that section on the rod at the stock width of 1/8"?
This interference thing is new to me.
 
You might try leaving it full size and knurling it lightly. It will then possibly be a nice press fit in your 1/8" drilled hole.
Depends on how close your drill bit will drill to the actual 1/8". And that's why reamers are used when a more precise sized hole is needed.
 
Given that you have limited tooling, I would do a couple of experiments. Try drilling the 1/8" hole in a test piece, and then see how the fit is to the 1/8" shaft. If it is too loose you may not be able to knurl it enough.

Or you could use the 7/64" bit, drill into the test piece, and machine a small pin that will just fit into the hole. You can now turn the shaft to a couple of thousands of an inch over that dimension for your press fit.

David
 
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