Did you make the forward-reverse lever yourself? Are there plans/drawings anywhere for it?
Yep, good idea. I'd need to take some material off the plastic control box (the lead screw shaft passes through it enroute to the change gear assembly) and there'd be some fiddling at the changegear end generally but that might be the easiest way to deal with this.
No plans or drawings. Other than a drill press it was done with hand tools and files, and lots of beer!
Good to see you got this worked out before I chimed in.Okay, wandered out to the workshop after work today. Popped in a 0.004" and a 0.003" shim between the apron and carriage and the movement was still a bit notchy.
Added a 0.001" shim and the notchiness went away.
Refitted the leadscrew, and leadscrew covers (coiled spiral thin springy steel tubes) and the covers, even when well lubricated, stick and make the feel of the handwheel inconsistent.
Took the leadscrew covers off.
All felt good with the handwheel. Plenty of clearance for the leadscrew around the half-nuts when not engaged.
So, I moved the carriage to the tailstock end and with fingers crossed and breath held, moved the tumbler for forward feed, engaged the half-nuts and switched on and slowly ran the rpm up to 300.
The leadscrew starts turning, carriage starts to move and the handwheel is turning as if it's being handled by the ghost of a long dead machinist. Turned the RPMs up to 600 and watched the carriage all the way along the bed. Nary a stutter; smooth all the way.
Now, there's been a full day/night cycle with temperature changes and I've messing around with the shimming and installing the leadscrew and testing so I fear checking but I give the carriage a bit of a rock. Still no play.
Success: the best recreational drug ever known; especially for an utter clumsy eejit newbie like me.
Next: fitting the cross slide and compound. I suspect I'll be buying some thrust bearings and machining the brackets to allow them to fit.
Fettling is an old perfectly honourable English (Northern dialect I believe, originally coming from a Norse origin) word. Nothing wrong with fettling.
I get where you're coming from.Fettling is an old perfectly honourable English (Northern dialect I believe, originally coming from a Norse origin) word. Nothing wrong with fettling.
Yep, I guess the correct (or 'cleanest' in software engineering parlance) solution would have been to relocate the rack the 0.008" upwards.
However, that would have meant reasonably accurately removing 0.008" of material from the top of the rack (meaning fabricating a jig for my cheapy little bench grinder), stripping down to the bed, working out a work holding solution for the bed on my bench drill press and then drilling new holes. That's kinda intimidating for a newbie like me.
Shims? Eh, I have the material and know how to use them.
(<<< theres a winky smiley here, but smileys don't work on this board for me)
Yep I understand what you're saying about general initial priorities and my instinct would be the same when dealing with any bugs I find in the code I write. What I've done by shimming is what programmers would call a "bodge"*.
You take constructive criticism and sarcasm well and don't get bent over any of this, so you have earned it.Yep I understand what you're saying about general initial priorities and my instinct would be the same when dealing with any bugs I find in the code I write. What I've done by shimming is what programmers would call a "bodge"*.
As you said in another post, I need (and want) to start making chips and learning to use this machine, so the shimming is a reasonably sensible solution.
I do have a "for my interest" question though, Both the pinion and rack teeth have been 'blued' so I'm not sure I'd be able to use Dyechem or the like usefully; how would you go about getting a 'print' of the contact? I guess the lead sheet would give some idea but it would be harder to get a granular enough picture of what's happening.
Also thank you for the support, it's much appreciated.
*given that it's easily removed and replaced with a better solution, it would be considered an acceptable "bodge" though.
If you're doing a lot of marking, there's proper stuff for that... For small, one time jobs, here's a couple of good weapons for you. A blue Sharpie marker and a silver Sharpie marker. By brand name. They dry, but wipe of of metal well enough to be plenty useful. Plus dirt cheap, and zero mess. And by whoever has it locally (auto parts stores), differential marking (or gear marking) compound, which is a bright yellow non drying proper marking medium.
I have some traditional honest-to-goodness, made in England, engineers blue (and God forbid you get that stuff on your hands, it never seems to quite dry, so you can leave blue fingerprints wherever you go if you're not careful but it takes serious cleaning power to get the stain out of skin!) but for parts that are already 'blued' or have some other dark surface, that won't show up.
but I find that sharpie ink tends dry too quickly to take 'prints'. I wonder if there's a version of Dyechem or the like in silver though; that would do the trick with dark ('blued' or anodized) parts (not from the company that makes the engineers blue I've got though; they'd not have any truck with any colour other than blue: "Why'd tha need tuh have anuuther culah than blew? It were good enoof fer me dad and me grandad...'appen it'll be good enoof fer tha" )