How to handle a D-shaft

Some garage door openers use a D coupler....

G'luck PaulS

Thanks. Looks like it's going to be the simple way. Probably fine for 1/4 hp.

I've got an old compressor head that I might try to make into a filing machine. About how many strokes per minute do you use?

PaulS

I bought the kit from MLA. As recommended, it'll run about 750 strokes per min.

Pete Keillor

Greetings Pete, I bought the MLA kit too, some time ago. How do you like yours? I built mine but made some mods. I really like mine. With the vee belt off I can grab the file and by pulling and pushing cause the drive shaft to rotate, even though Scotch Yokes are not made to run backwards. The steel part of the yoke, the part with the channel in it, I made from tool steel and then hardened, ground, and lapped to a very good finish. The bronze part that slides in it I made from aluminum nickle bronze, also ground and lapped to a high finish. With almost no clearance, just enough for oil, the mechanism works very well. I also used a bronze bushing with an oil groove in it for the drive shaft and a lip seal to keep the oil from leaking past the end of the bush. On the inside of the main casting I machined a hole with a little reservoir that feeds the drive shaft. The reservoir is filled from oil splashing inside. The basic design of the filing machine is, I think, very good and I like it a lot. Oh, I also added a couple taper pins that lock the table square with the supports and hence square with the file. Eric

I like the kit, although machining cast iron is nasty. I did it pretty much as drawn. Decided to try a flat belt just for fun. Working on the drive pulley now, won't take long. Crowning with a taper attachment is easy.

I bought a two piece pot collet for finish the cap, I was getting frustrated trying to chuck the mostly finished cap in the four jaw. But now the collet body won't thread into my homemade draw tube, although it will into the ones for the Hardinge mill. I'm going to have to open up the threads on the homemade one a little, which I hate (re-registering the threading tool on an internal thread). Oh well, if I mess up, I have the stock for another.

After that, it's paint it and run. Oh, and make a couple files.

Pete Keillor

You may find re-registering the bit in the internal thread easier if you set the compound parallel to the ways so your X and Y adjustments don't interact. 29 degree infeed isn't as necessary for light cuts, and you can imitate it by feeding both.

I bottom the bit in the groove visually and then take up X slack while turning the spindle by hand until the bit starts to shave a chip. It's easy on a back-geared belt drive South Bend.

-jsw

Good tip, thanks. I'll report how it works.

Pete Keillor

In case you haven't tried picking up the thread yet another thing that works for me is to do as Jim suggested with the compound but I like to try bottoming the tool in the groove by moving the coumpound a little in either direction (taking up backlash of course!) until I find the bottom of the thread. Set the X axis dial to zero at this point. Then use Jim's method of slowly turning the work while slowly advancing the tool in X and seeing which side of the thread the tool picks up and how far from the bottom of the thread you are when the tool just starts to cut. Looking at the X axis dial you will be able to see how far from zero you are and can then move the compound in Z the correct amount to allow the tool to bottom. Eric Eric

I just finished following Jim's suggestion. It worked well, the collet body just fits, and now I won't have any tight collets (had a couple).

Pete

I did too, which is why I figured out how to repair their threads.

-jsw