My "NEW" Prazi SD400 Lathe build

[RaisedByWolves]

Now on to the hand wheel proper.

I looked high and low for a decent, cheap cast iron hand wheel for this project and could not find anything “cheap” that was anywhere near “good” so I had to actually spend money.

Everything I found for a decent price was either an old quality hand wheel that would need extensive clean up and fitting or new production units that were in a vaguely round shape.

Found this really nice (Seriously really nice) one from a company I’ll mention as soon as I remember their name. It was $80 with shipping, but worth every penny.


Even with this being nice it’s still a cast and hand finished part, so it took a lot of indicating and fretting (fettling for you “Chap”) to get it within .005 of Od to Id but I figure that should suffice.


First order was boring out the hub from .375 to .395, or 10mm if you need that pesky kind of metrology.


I set it up with a carbide insert/carbide shank boring bar and went at it. The black marker lines are the tik lines left from when I was indicating this in the lathe.









I used pin gauges to sneak up on the final size, and stopped with a tight slip fit on an .394 under pin. 10 monkey-meters works out to something like .39372547904321 or some such.









With that done I moved on to the less delicate part, bringing the outside of the hub to size and squaring the face with the newly formed bore.


Meager beginnings.









And the finished hub brought to size at .900.










Checking the DDR adapter for fit I found I had just about. 001 Clarence. Perfect to fix it with a bit of the green elixir.











Here you can see the adapter in place with the DDR in on it and you can see the gap for the dial adjusting springs.








And the final product in place.












A neat benefit of this was that the new hand wheel is dished more and allows more room for my fat fingers to get between the hand wheel and tail stock to make adjustments easier.


There’s about 3/8” more wiggle room.










I still need to cut a keyway in the hub, as I’m waiting for the key cutter to arrive, so it’s not quite done, but good enough to try out.


Overall I’m stoked with how this turned out, and how much better the lathe looks with the new hand wheel. It’s amazing how smooth the operation is with the screw supported by 3 bearings and how much better balanced the entire tail stock is with the extra weight opposite the chuck.


I was undecided as to whether replace the carriage wheel with this exact same one, but I’m pretty sure my mind is made up on that now.

 

[woodchucker]

Here you can see the adapter in place with the DDR in place and you can see the gap for the dial adjusting springs.

Can you show a pics for the springs? and the springs installed.
Unless those little rectangular things off the right where the washer is laying in the bed are the springs.

 

[RaisedByWolves]

Can you show a pics for the springs? and the springs installed.
Unless those little rectangular things off the right where the washer is laying in the bed are the springs.

Yes, those are them.

I thought they were common enough, then again my Clausing lathe has little coil springs that push the dial against the slide.

 

[RaisedByWolves]

Can you show a pics for the springs? and the springs installed.
Unless those little rectangular things off the right where the washer is laying in the bed are the springs.

Got around to final assembly tonight and took a pic of the springs in place. I had to put some additional bend in them as the action of the dial was too stiff with the new adapter. Not sure if its really that much bigger, maybe its the difference in materials with one being aluminum and this new part steel?

Anyway, I put some extra, probably 40% more bend in them, and things loosened up nicely. The black marker lines are the tik lines left from when I was indicating this in the lathe.











But wait a minute, there is a keyway in the hub now. Yep, didn't have the proper 3mm broach so I had to order a set.










Before I could broach these two pieces together I needed to make them one piece with some 638 loctite. I didn't need to broach the adapter, but did need to be affixed to the hand wheel so the friction dial would be a working part rather than just decorative, so I hit them with some loctite and smooshed them together for a couple hours in the big mill.








Next it was time to try out the new broach. I was torn between using the arbor press for this as there would be no "feel" in a 3 ton press with such a small broach, but then I hit on the idea of using the big mills quill as an impromptu press.



This worked perfect and gave me almost too much feel, but all in all it turned out to work very well.



Pushing it through.








And through again with the shim in place this time to bring it to the final depth. I hadn't added oil yet when I took the first pic, but you can see in this one there was plenty of oil used on this run through and as well as on the initial run through..








I was a little concerned about going through two different materials and especially with the total length of cut being nearly an inch. I was thinking the iron might fill up the flutes and prevent the steel from making a curled chip, but it turned out the cost of this hand wheel was justified as even the iron made a nice curled ship and not the typical iron dust.

You can see the chips nicely curled inside of each other, suggesting the hand wheel was made of Meehanite or some other high grade cast iron..








And I must have done something right as when all was said and done I had a broached keyway and the broach was still in one piece.







With the keyway in place I was able to do the final assembly on the tailstock and adjust it and it came out better than I had hoped.

Initially I was abit Miffed as the handwheel had a slight wobble and I had spent so much time trying to avoid this in my setup, but it turned out the fixing screw was just barely touching the end of the quill screw when I had initially tightened the fixing nut. I backed the screw off, we tightened the nut, set the screw and it worked amazingly well.






You cant the fixing screw in that pic as its pretty deep in the threaded hole and I may shorten the fixing nut a little as it kinda sticks out a bit, but well see.



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