EQ6 belt mod

[chrisshillito]

For a non-engineering layman, what advantage does this mod offer?

Switching to a belt drive will make for quieter high speed slews, remove backlash issues (so worth doing on DEC axis as well) and because there is one less component in the drive train should reduce the over all periodic error. If you opt for an integer ratio between pulleys you will also have a PE waveform to which PEC can be applied more effectively.

Of course whether any of these mechanical improvements actually deliver a measurable improvement will depend on your own astronomy aims.

Chris.

[daz]

Thanks Chris

I shall watch this thread with interest....

[George]

Folks!

This is very interesting. I assume that changing the bearings to real SKF (Swedish!) ones is also best to do at the same time, right?

One concern of mine is the flexure of the belts. Any ideas on that?

Looking for a Swedish supplier, and I know that there is one as I did get some 8mm belts and wheels for a project in 2004. I'll let you know what I find.

All the best from cloudy Sweden,

P

I doubt flexure will be a problem with the modern fiberglass reinforced belts of today providing enough tension is applied.

[beamish]

I doubt flexure will be a problem with the modern fiberglass reinforced belts of today providing enough tension is applied.

Actually that's a very good point and not something I've come across yet -How is the optimum tension attained /retained ?

[ncjunk]

George,

Just finishing up some programming on the focuser and cloud sensor and then i'll be looking at getting some bits for this.

I think i'll get a new cloud version out next week and buy the belt mode bits then.

Saludos

Neil C

[George]

Seeing as no dimensions of the EQ6 worm gear can be found anywhere I had no alternative but measure it in the flesh, easiest axis to dismantle is the DEC and here's the measurements.

The space in the gear housing should accommodate 6mm belts no problem and this seems the popular choice of people who have already done the mod. So the 2.5mm pitch 48 tooth pulley WILL fit in the housing BUT the pulley hub will have to be turned down to 20mm and drilled out to 12mm to fit on the worm shaft.

[ncjunk]

Ok, that sounds way to mechanical for me.. Drilling out and turning down??? Sounds like i need a lathe a fully functioning work shop.

I've had man flu the last few days so not looked at buying any of this yet.

[George]

Eureka,..... found a pulley and belt set that will fit without any machining other than re-boring the 12 tooth to 5mm and the 48 tooth to 12mm.

motionco_Pulleys & Belts_Aluminium MXL Timing Pulleys_Buy Online

Just put an order in

[ncjunk]

Hah! automatic country recognition the bane of my life! The website comes up with a default explanation in Spanish that this is the default configuration for osCommerce...blah blah...

So I imagine it detects I live in Spain but they don´t have it configured properly and it defaults to the only spanish page which comes as default.

Sorry to bore you all...I cuold have just put "the websites rubbish"...

Doesn´t work on a uk proxy either...

Edited October 2, 2011 by ncjunk

[ncjunk]

So...i need these then?

PL012AL Aluminium MXL Pulley, 12T, 3mm Bore £3.46 Price Info

PL048AL Aluminium MXL Pulley, 48T, 5mm Bore £6.61 Price Info

and a belt somewhere....

[ncjunk]

BMXL080 MXL Rubber Timing Belt, 80 T £2.76 Price Info

..and one of the above?

[George]

2 x Aluminium MXL Pulley, 48T, 5mm Bore (Part PL048AL) = £13.22

2 x Aluminium MXL Pulley, 12T, 3mm Bore (PL012AL) = £6.92

2 x MXL Rubber Timing Belt, 80 T (BMXL080) = £5.52

Sub-Total: £25.66

Shipping: £0.00

VAT 20.0%: £5.13

Total: £30.79

Ive had the gears bored out and Im doing the deed today, hopefully I'll have it done today with some pictures

[ncjunk]

I will place the order monday, then i'll have to find someone to bore out the pullies. Let me know how the tensioning of the belt goes, thats the bit i am not sure about.

[George]

I will place the order monday, then i'll have to find someone to bore out the pullies. Let me know how the tensioning of the belt goes, thats the bit i am not sure about.

Tensioning was easy.... I measured the centres of the old gear set up and used the online belt chooser with the dimensions I had so the belt fitted perfectly. Getting the blumming belt over the small pulley was a challenge, I ended up putting a elastic band thru the belt and looping it over the motor then waggled the motor in.

Well pleased to say thats the DEC sorted and works fine, now got to dismantle it all again to lubricate everything

[SlipperySquid]

Reading this with interest,would love to mod my HEQ5. so really interested in what results you manage to get from this. Keep up the good work gents! and get the piccies up pronto

Matt.

[ncjunk]

George,

How did you remove the oldgears from the stepper motor? I have seen a picture of one that has a largeish brassish nut to undo but on mine this nut looks like a button i.e. No where to attach a spanner...unless the nut is underneath.

I am suffering a few high frequency errors on my RA so hoping this will solve it.

Does it sound good/quiet?

Well done by the way!

[malc-c]

George any chance of some pictures of this mod as you progress, this sounds really great and, as I assume there is no stretch in the belts, this eliminates backlash and PE ??

Like Matt, it would be interesting to see if anyone has done this with the HEQ5 as well

[George]

George,

How did you remove the oldgears from the stepper motor? I have seen a picture of one that has a largeish brassish nut to undo but on mine this nut looks like a button i.e. No where to attach a spanner...unless the nut is underneath.

I am suffering a few high frequency errors on my RA so hoping this will solve it.

Does it sound good/quiet?

Well done by the way!

Pictorial posted here http://stargazerslounge.com/diy-astronomer/159157-eq6-belt-drive-modification.html#post1980540

The larger gear on the stepper has a hex grub screw that has to be removed before you undoe the big nut

[Euan]

Hi George, how does this perform in the field?

I'm considering it myself as well as high precision replacement ring & worm gears. The thing I like about it is you can always reverse it if it doesn't work out

[ncjunk]

Hi George, how does this perform in the field?

I'm considering it myself as well as high precision replacement ring & worm gears. The thing I like about it is you can always reverse it if it doesn't work out

i had an error on mine and reversed it. i kept getting problems adjusting it and sudden jumps while guiding.

the sudden jumps in guiding turned out to be the adm saddle and the problems adjusting where because one of the pullies was rubbing against the side. when you take the pully down to 13mm make sure you check it...you can always take of 1mm more.

i found all this out after i had stripped it to put the gears back in but i will definately have another go sometime. i just want a non stripped mount for a while.

Apart from the stupid adm not being tight the mount was smoother and quieter. guiding on a c11 at f6.7 was very nice.

i would say give it a go if you like playing.

Edited April 29, 2012 by ncjunk

[Earl]

i had an error on mine and reversed it. i kept getting problems adjusting it and sudden jumps while guiding.

the sudden jumps in guiding turned out to be the adm saddle and the problems adjusting where because one of the pullies was rubbing against the side. when you take the pully down to 13mm make sure you check it...you can always take of 1mm more.

i found all this out after i had stripped it to put the gears back in but i will definately have another go sometime. i just want a non stripped mount for a while.

Apart from the stupid adm not being tight the mount was smoother and quieter. guiding on a c11 at f6.7 was very nice.

i would say give it a go if you like playing.

How do you guide your C11, I found that a ST80 didnt do the job for me

[ncjunk]

How do you guide your C11, I found that a ST80 didnt do the job for me

TS OAG although finding a guide star is a bit of a...pain..the OAG is fixed so no rotation (motorised rotation that is as i control from the house) and i always seemed to be guiding on stars at the limit if S/N ratio.

But the detail is great. my only problem now is that after slewing pointing was 2° out which is way too much for my automated software so need to sort out what is moving during slew.

i need a mesu mount to put more scopes on!

[Euan]

i would say give it a go if you like playing.

Bits ordered. Just doing RA, so for £18.85 it's a no-brainier

[PortableAstronomer]

I've decided to go ahead and do the mod on my EQ6.

Just received the parts, but during the manufacturing of the 12T pulleys, the holes were not centered. I received wobbly pulleys from the factory.

Hopefully it was just a one-off, and that others on here recieve good parts.

I am going to see if I can send it back and get it exchanged. Annoying because I have it post it back from Netherlands to UK.

I'll let you know how my mod goes when I've finished.

By the way, did anyone use a reamer to get the bore diameter to fit snugly on the shaft, or did most of you just use a standard drill bit on a lathe?

Clear skies

Edited June 4, 2012 by PortableAstronomer

[jackrussell0232]

Gents,

Have just done mine, but went for 15/60t pulleys to avoid the snag with the 12 tooth being a bit small to bore out to 5mm. Because I wanted to experiment a bit, I went to town on it, as you'll see.

Had some issues, but is looking really good now. The PE traces on my site are totally honest and raw (ie no low pass filtering in PECPrep). They show that well-centred pulleys eliminate all the gear-train-induced components in the PE trace. Mine ended up with no graunching noise when the motors start/stop (thank god - this was truly awful), and an FFT trace with the only significant input from the worm.

I quite like the colour now too.

See my site http://www.alphageek.co.uk

Wouldn't have attempted it without all the info on here, so many thanks to you all.

Regards,

Jack