tormach 1100 series 3 not making round 1in dia 1/2in deep holes

[mountaindew]

.026 loss of motion before now less then .0005

it apparently has been going for sometime and giving it a good bump did it in. i use to always have to play with my cam and cad to get stuff good enough for stuff to fit in a hole. since doing the repair now when i want to mill 1.001 it mills 1.001 which i didnt think was possible.....it sure makes things much easier to work with.....now i am going back to all my cam and tweaking them so i am not over compensating which is a good thing..

My mill is right at 0.0009 on the Y axis 0.0004- on the x axis. Might not be worth this much work to get 0.0004 better backlash "maybe" by replacing a 500$ ball screw. I have a bearing set for x and y axis now. Looking at it I want to replace my Y bearing set "because I think with new bearings I can tune the pre-load a little better" Just need to order new washers and maybe castle nuts. My Y units are beat up from me checking and testing preload a couple different ways a few years back. Then fix oil line or lines!

what i ended up replacing was the double bearing set for the preload on the y-axis $40 for the set tormach # 30430 and the complete y-axis ball screw with nut $525 tormach # 30448. you can not just purchase the ball screw nut but you have to get the complete matched unit. the oil line can be attached from the top just under the back bellow.
blessings!
craig

Thanks for the extra info and blessings! I know this is no where near as easy as your text above For couple years now I was thinking I should put some lift blocks under my mill so I can clean and get a hand under there for maintenance work on lines and check Y axis ball screw mount bolts. I have found those to be less then tight in the past .

[cncbuilt]

I guess it comes down to if you mill a 1” boss and measure all around the dia is it close enough for what you do? With that said I agree with your comment bearings might be wise and they are not very hard to do.

Yeah those bolts should be checked that could also help out a bit. Be careful though in that they are tiny and snap easy which happen to me then I had to drill it out . I was amazed that all the bolts involved where so small. 6 to hold the nut and 4 to hold he nut housing. I think they where only 4mm if I recall correctly.


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[IMT]

My mill is right at 0.0009 on the Y axis 0.0004- on the x axis. Might not be worth this much work to get 0.0004 better backlash "maybe" by replacing a 500$ ball screw....

Are those values the lost motion between the spindle and table? If so that is well within the spec of a new Tormach and you probably don't have any backlash in the ballscrew/ballnut.

[mountaindew]

Are those values the lost motion between the spindle and table? If so that is well within the spec of a new Tormach and you probably don't have any backlash in the ballscrew/ballnut.

Yes and yes Looking at ways to tune a little more precision out of the machine.

This machine will be in my crib for a very long time and I want to get the most out of it. I think early next year I will take the machine apart like keen and others have. Clean and inspect everything then a careful assembly of the machine "not assembly line built". I have been researching this carefully, putting together a parts list and thinking about what parts I want to replace and possibly improve, like way cover mounts. Another project on my list that needs to be done.

[mountaindew]

Tormach blog posted a brief article on acceleration and interpolation accuracy.

I asked about the subject of slowing speeds and feeds down to improve accuracy a few months back and didnt get much info. This helps confirm what I did late last year to make my single point threaded 6-32 screws and a host of other little round parts more accurate. I was thinking it was a little part distortion. Bob mentions a good idea of flipping tool paths that I didn't try! Easy enough to add another spring pass the other direction, Might have to click a few more times in sprut to do that with a with single point thread cutter. Wonder what works best top down first pass then bottom up second pass?
Anyway some good info for people that read this sort of stuff

[Steve Seebold]

Why won't you show us the code used to ruff and finish the pocket?