Thread: More (mad?) Mars Mods

I have super powers don't you know.

Going to be a little hard to disengage (I assume you're working out the dog lengths you can get away with?)

Are you going to operate on the selection fork directly or have some sort of collapsing link so you arent driving on the tips of the dogs?(again maybe over thinking this for the amount of use guys like us are going to give it?)

Stuart

Dogs are only 4mm (thats all i can fit in), i'm planning to taper them too, but am not sure of the angle yet (8 deg is classed as self releasing for arbors-i wonder if this relates to other uses?). Mind you, if you dive into the depths on PM there are pics of a Hendey's dog clutch, nothing fancy there at all. Hendey 14 by 6 Tie-Bar Rehab - Page 2

I guess i will find out....

Merry Christmas!

Ew

Originally Posted by Stustoys

Hey Ewan, Phil,

Did Phil get a copy of 17 yet? Would you believe someone ordered a copy and then thought it would be a good idea to check if he already had a copy............Some may say that was the wrong order and I would tend to agree with them.

Something looks wrong with that gear to me.... but then I wouldnt have a clue so I've been waiting to see it finished!

BTW Its not a bench

Stuart

Hi Stuart,
I also received a full digital copy of 17 from Bryan.
They are heaps easier to read than Machinery's Handbook.
Now you have got me worried because at one stage I went mad buying the Workshop Series of books. I really should make sure I don't already have a copy.
If by some miracle I can get a chance to sneak out to the shed I will have a look, and that would be a miracle
Merry Christmas everyone!!
Time to go open some presents. Woo Hoo!

Phil

I think I'm going to have to pull the top off my lathe again, I like the idea of one of these and think it may just be possible to squeeze one into the gearing and selector that is already in the headstock, with a couple of mods of course.

Stuart

So i have the dogs on now, just machined square for now. I will test them and see how they engage/disengage under load. As i understand it they are not meant to be engaged at high speeds, only low speeds. Nothing stopping you from disengaging them at high speeds though (except the force required maybe).

I have the head off the lathe now and have machined the front face somewhat, and bored a hole for the clutch lever to go through. I set the head up with the spindle in place and dialed it in so it was parallel with the X axis. I also made sure my mill table was trammed too (now that is a bitch of a job.....much harder than tramming a head). Time to work out whether i need a full yoke or just a single brass block to push on the clutch (comes back to the force required i guess). Then i need to work out how to add the knock out rod.

Cheers,
Ew

Well i now have a test bar within .0002" over 250mm. I put the head back on the lathe and put the test bar in the spindle. What the? The test bar has .004" TIR. I check the test bar on the tombstone in some v blocks. A barely perceivable .0001" runnout of the taper. I check the MT or the spindle, sure enough there is the runnout. Not only is it off center it is also pointing off the spindles axis.
I'm guessing someone has taken to it with a reamer at some stage and made a real mess of the alignment. So i can't really test the head as is, short of aligning the test bar on the tombstone first (after getting the spindle parallel to the plate), bolting the head to the lathe and checking it to the saddle travel. Better then boring it blind i guess. Boring it in situ on the lathe would be great but not so easy with the head not sitting on the T/S ways. I guess i may have to do some scraping to get the head in vertical alignment after sorting the bearings and re machining the MT. The bearings are in no state now to bore the MT.

Ew

I have been doing bits and bobs to the lathe over the last couple of months (didn't realize it had been so long). Ended up boring out the bearings on the mill, first setting the spindle true to the Y axis of the mill using the old bearings and then boring, bushing and boring to size. I didn't take any pics of the setup in the end, it was finished and broken down in a hurry to do a "real" job.

I then set the spindle up in the Antrac and trued the morse taper. With the head back on i have a bit of work to do with the spindle pointing to the sky by .006" over 8". The part of the bed the head clamps to clocks the same to the ways, some poor work there at some stage.

The dog clutch is now running, i had to machine 2 of the bevel gears down in diameter a bit as they fouled on the belt. I had made sure they cleared the pulleys but forgot about the rubber thing wrapped around them . The clutch is easy to engage/disengage under power, no problems with square faces.

The best/worst news is i have someone interested in the lathe who says they will buy it once it is running again......i've had a lot of fun working this out though!

Ew