lead screw deflection, carriage slide nut

M

macher

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101.07403, No power crossfeed and two gear covers model, probably made in 1938.

When I engage the lead screw lever it pushes the lead screw down slightly, but also causes the thread counter to disengage. Anybody have this problem?

The parts list calls for a 10F-19 carriage slide nut for the saddle. When I ordered one it is too big. Should I be using the same one that goes in the tool post slide, the 9-306?
 
Perhaps you still have the 5/8" leadscrew? All new parts tend to be for the 3/4" leadscrew.
Pierre
 
can you post some pic's of your lathe. The model # you posted doesn't seam that old.
 
I wrote the wrong model number. It should be 101.07402. It has a 5/8" diameter lead screw and no power cross feed.
 
Macher,

First, if engaging the half nuts moves the lead screw up or down, the lead screw is too low or too high. The right lead screw bearing height is adjustable. Move the carriage to a position near the bearing, loosen the two mounting screws, engage the half nuts (which should move the bearing up or down) and tighten the screws. Move the carriage to a position near the head stock and engage the half nuts. If the lead screw still tries to move up or down, I've never worked on any of the 12 pre-war models and don't know whether you can move the gear case (which determines the vertical position of the left end of the lead screw) up and down or not. Unless someone here already knows that you cannot, you could loosen all of the mounting screws and the quadrant (change gear bracket) clamp screw and try it. If there is not enough movement to cure the lead screw deflection, you will have to shim the carriage up. Attached to the bottom of the carriage are two bearing plates (front and rear). Between them and the bottom of the carriage should be a shim pack at each location. It appears (at least in the later models) that they were made in two thicknesses, 0.002" and 0.003". Note that shimming the carriage up also increases the engagement between the rack and the gear that meshes with it. So there is a limit to how much the carriage can be shimmed up. Note that if you do this (shimming up) and have a QCTP with holders with cutters in them that have been adjusted to the correct vertical position, you will have to readjust all of them.

The 101.07402 and earlier have a different carriage from the 101.07403 and later. Most (but not all) of the parts in the latter are 10F- parts, whereas the corresponding parts in the former are either 10D- or 9-. The part numbers for the shim packs (no indication as to how many shims in a pack and of what thickness) for the 101.07402 and earlier are 10D-159 and 10D-160. The part number for the early cross feed nut is 9-19, not 10F-19. The cross feed screw and everything associated with it except the Woodruff key and nuts are also different. Try Clausing with the earlier part numbers. If they don't have them anymore, they may still have the drawings. If they do have the drawings, they will most likely email you a PDF of them if asked.

Robert D.
 
The gearcase is fixed on the left side as it is mounted to the top of the ways.
You might be able to move the 9-13 Guide that holds the halfnuts a bit, but based upon the lathe I had there is not much movement available.

Another item is that on mine the top of the ways had been ground a couple times prior to my getting it and the carriage was sitting lower then factory and this would cause a similar situation with me. What I ended up doing is shim up the carriage to relocate it to a high position. Molice is the product you should look at if that is the issue in your case. You can tell by looking at the amount of engagement of the traversing gear to the rack on the underside of the ways. The lower the carriage the less the gears mesh properly.
Pierre
 
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pdentrem said:
The gearcase is fixed on the left side as it is mounted to the top of the ways.
You might be able to move the 9-13 Guide that holds the halfnuts a bit, but based upon the lathe I had there is not much movement available.

Another item is that on mine the top of the ways had been ground a couple times prior to my getting it and the carriage was sitting lower then factory and this would cause a similar situation with me. What I ended up doing is shim up the carriage to relocate it to a high position. Molice is the product you should look at if that is the issue in your case. You can tell by looking at the amount of engagement of the traversing gear to the rack on the underside of the ways. The lower the carriage the less the gears mesh properly.
Pierre
Click to expand...

Adding to that, visually look at the rack teeth near the left side of the bed where most of the use is and to the right side that seldom see's wear. If the rack is worn a lot then the rack pinion gear is probably worn too. So using the rack clearance when your measuring on a worn rack or a rack pinion has to be done carefully. If the pinion gear is to sharp and worn , better order one of those too. Some will reverse the rack, but I generally don't recommend that, so if the rack is worn, order one of those too. Or check with "Rush Gear" as they sell racks. You may want to measure the distance of the feed screw pitch (threads) and inspect to see if they are the same thickness using a dial caliber. Have you done some repair work on your machine to cause this problem, or has it always had this problem when you engage the feed 1/2 nut? (for those who don't know me, I'm a Journeyman machine tool rebuilder).

Moglice is a fine product, but Rulon could also be used. Rich

(Sorry Pierre I hit the wrong button when I added the info, the first time)
 
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I had thought of plastic product when I did mine but I used brass stock. I picked up some 360 at .125" and rolled it down to .085" to fill in the gap. I D&T a couple small countersunk machine screws to hold the brass stock to the underside of the carriage. Worked great. I renewed the wipers to minimize the likely hold of chips getting under and scrapping the top of the ways.
Pierre
 
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