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| PeterE:
Well, now I am slowly enbarking on a longer project on/with my C3 lathe. The project is of the kind that if one wants to do this, then one might just as well do both that and the other The means that I intend to put the saddle micrometer stop in place, but that requires that I remove the saddle to drill and tap the fastening hole, and to remove the saddle I have to remove the apron and lead screw as well. All in all this amounts to several things to be done in sequence: - Strip down the saddle, apron and leadscrew - Make a swarf guard for the apron hand-wheel gears - Update the hand-wheel like the MEW example but with my own scale ring - Fit the saddle micrometer stop - Make and fit a saddle lock - Fit the saddle and adjust backlash to as little as ever possible - add ball bearings to both leadscrew ends - Add a dis-engageable hand-wheel to the leadscrew. So right now I am trying to make all the needed parts in advance while my C3 is still assembled. The first bits produced are the parts for the right hand leadscrew bearing and the leadscrew hand-wheel. The following pic shows the bits: The black thingy is the housing (sorry for the bad photo angle).The lower row from left to right shows: - The extension sleeve that I add because I want to move the whole assembly to the right with about 20 mm to gain extra travel for the saddle and a good position for the leadscrew hand-wheel. - left ball bearing which is a 12x28x8 bearing, - an inner ring distance and the right ball bearing (same type). - Then the leadscrew extension. - The lock nut pushing the bearings together to eliminate backlash. - Finally a dial that will fit over the hand-wheel and cover the lock nut. The fiducial line will be on the housing. The shown dial will be replaced with one that is a bit wider but it will look the same. This dial will go on the apron hand-wheel instead. A trial assembly of the parts without the hand-wheel shows that it will be a quite compact assembly in the end. As you can see, there is no fastening screw on what will be the underside. This is because the bearing has been moved past the "leg" on the right side and there is nothing to put a screw into so there are two screws at the top and two guide pins to fix the bearings position once it is fitted. Adding the hand-wheel, the whole setup will look something like this (but not nipped in the bench vice) This pic shows more clearly the fastening holes. I choose to make the extension sleeve slightly conical because then I think/hope that if I run with the leadscrew clamp closed for left-hand threading for example, the clamps will be forced open when climbing on the sleeve, but whether it works remains to be seen. Anyway it looks nice BR /Peter |
| andyf:
That looks like it will be effective, Peter, though I think the design of the half-nut engage/disengage mechanism in the apron is such that the cone won't act as an emergency stop. But if you manage to stop in the right place and avoid crashes when the saddle is moving towards the headstock, you will avoid them when turning the other way or LH threading, which probably won't be very often. How are you going to add a bit of friction to the dial? The easiest way would be to squeeze an O ring between the dial and either the handwheel or the locknut - less likely to fly into a black hole than the bits of spring steel the manufacturers fit to their dials. One thing you might consider is filing a flat on the extension shaft where the grubscrew in the handwheel will bear on it. Besides giving a more secure fixing, this will avoid the problem of the grubscrew roughing up the cylindrical surface of the shaft, making it difficult to pull the handwheel off. Andy. |
| PeterE:
--- Quote from: andyf on August 27, 2011, 07:16:26 PM ---That looks like it will be effective, Peter, though I think the design of the half-nut engage/disengage mechanism in the apron is such that the cone won't act as an emergency stop. But if you manage to stop in the right place and avoid crashes when the saddle is moving towards the headstock, you will avoid them when turning the other way or LH threading, which probably won't be very often. How are you going to add a bit of friction to the dial? The easiest way would be to squeeze an O ring between the dial and either the handwheel or the locknut - less likely to fly into a black hole than the bits of spring steel the manufacturers fit to their dials. One thing you might consider is filing a flat on the extension shaft where the grubscrew in the handwheel will bear on it. Besides giving a more secure fixing, this will avoid the problem of the grubscrew roughing up the cylindrical surface of the shaft, making it difficult to pull the handwheel off. Andy. --- End quote --- Hi Andy, Thanks for comments and suggestions! Whether the cone or slope on the extension sleeve will actually work as an emergency release I really cannot say. It would be useful if it works, but I actually don't think it will because the lock on the engage/disengage mechanism is probably more powerful. To be honest, I designed the sleeve to look nice and afterwards saw a possible functionality within the design. :loco: The friction to the dial(s) will be made using O-rings as being the simplest way forward. To lock the hand-wheel my thought have been to drill a shallow hole suitable for a dog point on the lock screw (thumb screw) that will lock the hand-wheel to the shaft, but as you say, it might be better to just make a flat to lessen the risk of burrs of any kind limiting the movement of the hand-wheel. Thanks, I must think of this some more. BR /Peter |
| PeterE:
Since this project includes dismantling the apron, removing the leadscrew, and other things, I need to make and fit a saddle lock. This to be able to turn stuff even if the apron is off. Having searched for ideas I have seen three major solutions, the first is to add a clamp to either the front or rear right or left corner of the saddle, the second is to fit a single lock in the middle right using a tab going in under the saddle, and the third is to fit a locking screw through the right free side of the saddle. Option 3 goes for WIESS or REAL BULL machines, but mine is a SIEG machine so that leaves two variants. A lot of thinking about goods and bads, I have ended up with this idea. Fitting a piece of mild steel in the opening to the right and securing it to the saddle using two M4 srews straight into the side. (...and now I can see that the drill wandered at of the holes :bang: ) I choose this way because I only need one locking point at the center. It will not try to skew the saddle under pressure (too much) and it will be fairly easy to fit without having to remove the saddle from the bed. I will be using an ordinary hex-head screw to avoid having to clear the head for a hex key. Now, before making holes in the machine, I would like to ask the readership for more goods or bads with this way of fitting the stop. BR /Peter |
| S. Heslop:
This is how I made my saddle stop. It's perhaps a bit hard to see whats going on because it's just a sketch, but the dashed line going through the two holes is where a bolt goes and the bottom bar's hole is threaded. The thing is just a removable clamp that pulls the saddle down on the ways, and avoids having to drill holes in the saddle. Thing is that with so many wonderful and elaborate saddle stops out there I feel this is just too simple to work brilliantly, otherwise somebody else would've already thought about it and published the idea. So i'm not too confident in it. |
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