final eq6 mod results-what do you think?

[garymck]

Hi,
for those of you following my eq6 travails in
http://www.iceinspace.com.au/forum/showthread.php?t=58729

Here are the final results of my latest internal belt drive mod. I'm feeling too close to the issue to make a rational judgment about it. This was a one way mod as the worm had to be turned down to fit the pulley...

Do you reckon it's now a keeper? or should I get rid of it- have a couple of Iceinspacers who are interested in it even though they know of its deficiencies.

pics are of pe and fft before and after belt drive mod.

Gary

[peter_4059]

Gary,

The PECprep results look similar in terms or RMS PE however it looks like you've got rid of the transfer gear errors. You could get a replacement worm if you want to revert!

Peter

[bojan]

Hi Gary,
I am very interested in how you mounted the belts inside,since I want to do something similar (http://www.iceinspace.com.au/forum/attachment_browse.php?a=67161)
Could you post some pics or drawings?
The PE curve looks quite OK to me, those small sudden jumps (47 of them per period) were exactly what bothered me as well.
The rest is probably easy to remove with autoguider.

[garymck]

Hi Bojan,

I simply used the stepper that was in the mount, fitted the new pulley after removing the transfer gears. The worm was turned down on the side that the pulley was mounted to make it easier to fit the pulley - it is wider than the standard gear) , also had to dremel out the slot the gear protruded through a bit so the pulley could fit. The pulleys are 2.5mm pitch 47tooth and 12 tooth from the link I posted in the older thread. Have no pics...don't want to take the mount apart again :)

cheers
Gary

[bojan]

Hi Gary,
Thank you for this..
I was pretty sure the slots are too narrow for 3mm belt and should be widened a bit.
Did you use 3mm or 6mm belts?

[garymck]

Bojan,

the belts I used were 4mm, however if I was doing it again I would use 6mm ones just for the extra resistance to stretch. I haven't noticed any backlash due to this yet, but I just feel I would like the extra security of a wider belt.

cheers
gary

[bojan]

4mm is probably OK.
After all, the whole thing must be balanced anyway.. the only issue is fast slewing (and if there is no proper implementation of acceleration in the firmware).
My EQ6 has only 16x and 24x slew rate (no acceleration.. Darren's modification) so I am guessing even 3mm belt may be OK. If this proves not to be the case, I will use 6mm belts :-) (or 2x 3mm in parallel, however this option may prove to be more expensive).

BTW, I would turn the pulley, not the worm. It is always a risk of having something un-concentric when performing additional machining on the other than original lathe (unless you use pins for centring).. and the worm is much more expensive than pulley to be replaced.

At some stage I was considering steel chains.. but I could not find anything appropriate (narrow and small pitch enough)