Melbourne lathe work - Small job

[graphworlok]

I need a small amount of work done on a lathe - I need a shaft coupler made up to connect a pulley to my mounts declination adjustment shaft

(So, a bit of round metal roughly 15mm diameter, 30mm long, with an (roughly) 8mm hole through the center, and two holes for grub screws through the side to fasten the two shafts in place)

I have one that a random internet person was kind enough to make and post to me for free, but unfortunately the holes are mis-sized/out of center enough that the belt drive seems to slip each revolution

I'm attempting to add guiding capability to an old EQ3 with clock motor that i bought on ebay a year and a half ago

Can anybody offer me their time, or recommend a machine shop that could be bothered with this piddly bit of work?

[Terry B]

Try posting here (http://www.woodworkforums.com/f65/)

and asking around.

[gary]

Hi James,

Are you sure about the "roughly" specification? :)

In most applications of this nature (you do mention guiding as a goal)
you will want to achieve a transition fit between the shafts and the coupler.
Otherwise if the fit is a very loose clearance fit, the mating parts might pirouette
around a little when you tighten the set screws onto the respective shafts. This
will introduce guiding errors.

Ideally you would have the shafts to be mated nearby the machining operation
so that the machinist could check the fit. This may not always be practical if the
mating parts are firmly fastened to the rest of the mount and the assembly is too
large or awkward to bring over the bed of the lathe to check. In which case
the machining would be done on the bases of metrology, the operator would probably
initially undersize the hole by a tiny amount and then possibly use an adjustable
hand reamer to widen one end at a time a little at a time, the whole time continually
re-checking the fits for both respective shafts.

In a nutshell, the "roughly" specification might provide enough scope for disappointment
and might be an obstacle for someone putting up their hand to volunteer unless they
happen to live near you. :thumbsup:

Best Regards

Gary Kopff
Mt Kuring-Gai

[scopemankit]

If it is merely a shaft coupling, try petrol tubing and clamps (home-made)

[bojan]

Yep, this is a right approach.
It will also reduce the vibrations and noise from steppers.
Instead of metal clamps, I am using nylon cable ties.

But, if you are perfectionist, try this:
http://shop.ebay.com.au/?_from=R40&_trksid=p3907.m570.l1313&_nkw=stepper+coupler&_sacat=See-All-Categories

[graphworlok]

Thanks everybody for your ideas!

I have already had one offer from a kind member with a lathe, and will probably make up a rubber coupler as well to compare the two -Given that this is for my homebrew Dec. motor on an EQ3 (for a homebrew autoguider rig), i'm not sure which will work best

[scopemankit]

"I am using nylon cable ties." - Bojan


Thanks for that Bojan, great idea. I have since modified it using3.5mm silicone rubber sheeting.

[GrampianStars]

Sorry to hi-Jack this thread
I have a flat stock Al bracket
that needs to have a 1/4" deep section routed out
anyone in the western suburbs Melbourne have a lathe? :help:
p.m. or ph: 0418 390 600

[Gama]

Hi Rob,

Im in Sydenham, and i have a lathe and Milling machine, so call me on 0414 666877 to discuss your "little" job.

Theo