Re: flexible couplings for PCB router

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Alan Marconett" <KM6VV@...>
wrote:

>
> Hi to the list,
>
> I'm designing and building a small PCB router, gantry style. Size

is about

> 12" W x 12" L x 12" D. I'll be using stepper motors; this project

was to be

> "from stock on hand". I salvaged a couple linear slides.
>
> I also found linear bushings and precision shafts on E-bay that look

to do

> the job, I thought I might as well find commercial parts as well.

The lead

> screws are another subject!
>
> I'm familiar with helical beam couplings (my CNC'd Sherline has them).
> Anyone ever use slotted disk couplings, also known as Oldham

couplings?

>
> McMaster Carr under couplings:
>
> Hub 3/4" D. 7/8" L. 3/16" to 1/4" shafts. 59985K2 $8.02, 2 ea.
> + disk 59985K62 $1.46 or 59985K92 $2.29
>
> Helical couplings:
> 3/4" x 3/4"; 3/16" to 1/4" 6208K4 $20.50
>
> Not cheap!
>
> McMaster says neither have backlash. The Oldham couplers would make

it much

> easier to assemble/disassemble. Seem to tolerate similar

miss-alignment.

>
> Looks like I'll be mounting the NEMA #23 steppers on short threaded

rod. I

> really like the Sherline mounts, but other then using a piece of

pipe for

> the standoff and LONG bolts, I don't have a similar design in mind.
>
> Alan KM6VV

You can make your own helical coupling from aluminum and a jewelers
saw. just make a small ficture to hold the blade on your lathe and
then another to hold the part on the cross slide.

really neat is that when you get the saw moving at a nice slow speed,
the cutting oil is wrung to the outside, but does not fly off.

As for the mount, you can make them in a few ways.

one is to use box tubing. cut it for the stand off and then make
plates to attach it.

or, you can take 3/4" bar and drill and tap it on both ends and mount
plates to that.

Dave