SMW Shop / My NEW Hobby

[rob_b]

Quick and dirty fix, make some short standoffs from 1/2" or 3/4" diameter aluminum and bolt the motor on as is. Machining the threads off and facing the end shouldn't be difficult either as you are under the hardened depth. Should cut like butter

[rob_b]

Here is my home made version. 1/2" round bar.

[rob_b]

I can take shit apart like a nascar pit crew. It's the putting it back together that takes me forever...

Let's get to it. Start by excavating the mill. It had actually bonded itself to the stand!




12lbs of mostly Delrin and 7075. It's been awhile.




Column broken loose from the base.




Previously tried some little homemade brass tipped set screws. Two of them don't stand much of a chance against the four main connection bolts. Lesson learned, don't believe everything you read on the internet. Going to use shim stock this time.




Since I'm starting totally from scratch again on the alignment I decided I can't continue without a granite square... see, putting shit back together not so much.

[Crawling Calvin]

As for shim stock... don't go for brass obviously . Try and find some hardened stuff like for "feeler" gauges or whatnot. Maybe not the cheapest but you can get that sucker dialed in. Best of luck on it and remember... half the "fun" is the re-engineering

[rob_b]

I have a small box full of 12" Starrett feeler gauges that came with one of my tool boxes...

Just ordered this cast iron ground "angle iron" from Shars. All faces parallel within .00025" per 6" and square within .0005" per 6". Hope it really is that close for $34. Lol

http://www.shars.com/products/view/5...Iron_4x5x6quot

[rob_b]

Well that was an exercise in patience and procedure. First square the column to the Y axis, required a .002" shim that actually leaned the column toward the operator. Not what I was expecting. Tap the column left and right (bolt hole clearance allows a few degrees of movement) to square it to the X axis. Then lock that sucker down! Checked the tram of the spindle again. .008" off in Y still. WTF? Think about it for a while and decide that the spindle centerline must not be parallel to the head stock/slide interface. Required a .007" shim that tilted the top of the spindle away from the operator to tram out the Y axis. Now more tapping on the head clockwise/counterclockwise to set the X axis tram. Lock down the head. So now the head movement and spindle tram are square to the X-Y axis within .0005" across 4.5" Next up I would like to get the limit switches mounted. Then make some parts!

[BigSki]

Originally Posted by rob_b

Well that was an exercise in patience and procedure. First square the column to the Y axis, required a .002" shim that actually leaned the column toward the operator. Not what I was expecting. Tap the column left and right (bolt hole clearance allows a few degrees of movement) to square it to the X axis. Then lock that sucker down! Checked the tram of the spindle again. .008" off in Y still. WTF? Think about it for a while and decide that the spindle centerline must not be parallel to the head stock/slide interface. Required a .007" shim that tilted the top of the spindle away from the operator to tram out the Y axis. Now more tapping on the head clockwise/counterclockwise to set the X axis tram. Lock down the head. So now the head movement and spindle tram are square to the X-Y axis within .0005" across 4.5" Next up I would like to get the limit switches mounted. Then make some parts!

[SMOKEY]

i know a guy that could wire said limit switchesand works nearly free

[rob_b]

I should be able to handle the wiring as its a single RJ-45 into my controller They are proximity switches and I paid a bit more for the turnkey setup. Just need to come up with sensor mounts and target flags.

[JohnRobHolmes]

I've been running blind on the taig, switches are a really good idea! You using inductive sensors?

[rob_b]

You have just surpassed my electronics knowledge! But, the answer is apparently YES.

Inductive Switch Assembly to RJ45

[JohnRobHolmes]

Inductive is pretty repeatable and works well with most metals, its a great choice that won't break the bank!

[rob_b]

Limits have been installed for a week or so. Slightly rushed and ghetto but they seem to be functioning perfectly. They have also highlighted a weakness in the mill that has bugged me from day one. Which is the mechanical backlash in the screws/nuts. Working on some designs to fix that...






Mechanical is done on the tapping machine. Was able to get the motor mounted with no modifications to the casting. Made a solid coupling for now (free) to test function. It might shake to death at full speed as I didn't indicate the two bores concentric. Need to start the electrical next.

[Duuuuuuuude]

Ball screw or just threaded screw and nut?

[rob_b]

Ball screws

[Crawling Calvin]

Originally Posted by rob_b

Ball screws

There is ways to do it where you pack larger balls into the races but that causes things to bind more easily and it isn't that great an idea all around. Double-nuts with preload are used on big machines and it works well from what I can tell.

i use nuts with preloading down to .001" or less backlash ive measured the overall machine accuracy is another story

[Duuuuuuuude]

Depending on how the ball nut is constructed, you could diy a delrin preload nut to add onto it. Easy and cheap, but time consuming.

[rob_b]

Originally Posted by Crawling Calvin

There is ways to do it where you pack larger balls into the races but that causes things to bind more easily and it isn't that great an idea all around. Double-nuts with preload are used on big machines and it works well from what I can tell.

i use nuts with preloading down to .001" or less backlash ive measured the overall machine accuracy is another story

Current nuts have over-sized balls. Still have 2-3 thou of backlash. A double nuts design is what I am working on. Z axis will be a bolt on deal. X-Y will have to have some additional machining done to the castings to make it all fit.

Originally Posted by Duuuuuuuude

Depending on how the ball nut is constructed, you could diy a delrin preload nut to add onto it. Easy and cheap, but time consuming.

Preload nut will be from steel and use wavy springs to supply the pressure.

[rob_b]

Posted a similar design earlier in the thread but that was for a 3/8" ball screw. The mills Z axis has a 3/4" screw. From looking at other commercially available adjustable preload nuts I was shooting for a max preload of 660lbs. Using ( 8 ) wavy springs gives a max force of 688lbs. I figure it will just be a trial and error type of deal of finding the max force which does not introduce excessive drag.

[SkaldidDog]

Now that's my kind of complicated. I'd hate to hook a DRO system to my machine and actually see the backlash. Ignorance is bliss.

J