U30b chassis for Tillig Gear Tower

Re: U30b chassis for Tillig Gear Tower

Postby Bernd » Wed Mar 06, 2019 3:00 pm

Rob M wrote:
Bernd wrote:Sherline uses Lunix and the software running on the Sherline is EMC. I use CamBam for my CAM program. As far as I can determine from the manual there is no backlash compensation in the software. The machine has hardware backlash adjustment screws. See pic.

Bernd


You need to measure backlash with a dial indicator. Your hand is not sensitive enough to feel a few thousandths of an inch movement.

http://linuxcnc.org/docs/2.6/html/config/ini_config.html
"BACKLASH = 0.0000 - Backlash in machine units. Backlash compensation value can be used to make up for small deficiencies in the hardware used to drive an axis. If backlash is added to an axis and you are using steppers the STEPGEN_MAXACCEL must be increased to 1.5 to 2 times the MAX_ACCELERATION for the axis.


Rob,

I have to eat some crow here. I did do a hand check of the Y axis and it didn't shake. Reason? It was on a tight spot on the lead screw. I check both X and Y with an indicator. Traveled .010" back and forth. Found that the X axis was off exactly .010" and the Y axis was a total of .012". The bad news is when I tightened up on the backlash screws the axis would only moved where the machine has been running in that portion of the lead screws. Apparently I've worm the lead screws in that area causing the backlash to increase.

Solution? I just ordered two new lead screws at a cost of $61.00, includes shipping of $27.00 from the West Coast. Sherline has replacement "ball screws" for both X and Y axis but are close to $1200 I'll pass for now. If I'm going to make parts I guess I'll have to invest in those ball screws down the line sometime.

Thanks for your input.

Bernd
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Re: U30b chassis for Tillig Gear Tower

Postby Rob M » Wed Mar 06, 2019 3:08 pm

$1,200, ouch! I would bet someone has a cheaper solution.
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Re: U30b chassis for Tillig Gear Tower

Postby Rob M » Wed Mar 06, 2019 3:22 pm

Actually the solution I have on my machine only costs a few dollars. I have a weight and pulley system that puts a constant pressure against the nuts to hold them tight. All you need is some 100lb braided fishing line, a pulley and about 5lbs on each of the X & Y axis. Unless you are taking huge cuts in metal it should work just as well on your setup.
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Re: U30b chassis for Tillig Gear Tower

Postby Bernd » Wed Mar 06, 2019 9:00 pm

Rob M wrote:Actually the solution I have on my machine only costs a few dollars. I have a weight and pulley system that puts a constant pressure against the nuts to hold them tight. All you need is some 100lb braided fishing line, a pulley and about 5lbs on each of the X & Y axis. Unless you are taking huge cuts in metal it should work just as well on your setup.


I've got new lead screws ordered. Hopefully they'll be here in a week. Perhaps next year if I save up my pennies I'll look into getting the ball lead screws.

Here's the package for the conversion.

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So this project will be on hold until I get the machine up and running again.

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Re: U30b chassis for Tillig Gear Tower

Postby ConducTTor » Wed Mar 06, 2019 9:23 pm

Sorry gents but there will be no updates to the design. As mentioned elsewhere the file became corrupt. It's this or start from scratch (which I am not willing to do).


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Re: U30b chassis for Tillig Gear Tower

Postby Bernd » Thu Mar 07, 2019 9:34 am

ConducTTor wrote:Sorry gents but there will be no updates to the design. As mentioned elsewhere the file became corrupt. It's this or start from scratch (which I am not willing to do).
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Ah yes, I remember now reading about that. Not a problem, there's a couple of work a-rounds.

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Re: U30b chassis for Tillig Gear Tower

Postby Bernd » Sat Mar 09, 2019 5:24 pm

Looks like I'll have my mill back in operation by end of next week if all goes right.

Here's what I need to make a chassis for the Tillig gear towers on an .080" (2mm) thick brass. As I posted in the above 3D picture I'm going to cut pockets for the clips into the chassis. I've used Ian's picture and put some lines on it showing what I'll need for dimensions, center to center (approximately). The position of each clip from the rear and the length of a clip for the pockets, in other words how long. I'll mill the pockets to .040" (1mm) thick so they will fit under the clips.

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Re: U30b chassis for Tillig Gear Tower

Postby TiTan downunder » Sun Mar 10, 2019 4:59 am

Bernd, Sorry mate, did all this the other day then 'lost' the bit of paper.
The 'clips' are actually 3mm wide but if you can make the slots 4mm wide it will allow a small 'fudge factor' for easier fitting.
U30B.jpg

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Re: U30b chassis for Tillig Gear Tower

Postby Bernd » Sun Mar 10, 2019 7:56 am

TiTan downunder wrote:Bernd, Sorry mate, did all this the other day then 'lost' the bit of paper.
The 'clips' are actually 3mm wide but if you can make the slots 4mm wide it will allow a small 'fudge factor' for easier fitting.
U30B.jpg

Ian


Ian,

Nothing to be sorry about. Ok so will start with 4mm wide clips. That dimension from the left steps to the first clip will be 21.6mm. I didn't get the line in the proper place when I added the lines.

As soon as I get my lead screws and the machine back to gether I'll make one for you to try out.

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Re: U30b chassis for Tillig Gear Tower

Postby TiTan downunder » Sun Mar 10, 2019 4:11 pm

>> That dimension from the left steps to the first clip will be 21.6mm <<

NO - 20mm - I measured from inside the step. Should have left that 1.6mm out - added confusion.

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