George

Hi Malcolm,

I wouldn't worry too much that looks quite typical to me and shows the effects of the non harmonic standard gearing. I'll write up a short analysis report to explain exactly how to process and interpret the data within PECPrep.

Chris.

I look forward to that Chris, it's alright getting data (no chance here tonight its blowing a gale) but the knack is deciphering it

Im a bit baffled by the worm harmonics.....8 of them if you could explain what each of the harmonics refers too it would be easier to look for the problems that relate to them.

Ok here's the data I grabbed last night and below it the last data of a short session in August.

Im hoping Chris will pop in here and decipher it seeing as he wrote PECprep

To my untrained eye I'd say most of the errors I had are reduced by 50%, considering what the modification cost and the time involved I'd say it was more than worth doing.

If I could figure a way of including the logs in this post someone might be able to decipher them better

I only had a small cloud free window tonight and I desperately wanted to grab some quick and dirty data, Ideally you should grab PHD data with guiding turned off but I wanted to compare old data with new data and as I had no unguided data I had to do a guided comparison, not ideal but.......

Also looking at the above graph have you tried guiding the dec in only one direction? Made a hell of a difference on my system as eliminates over correction.

Someone mentioned it on SGL and i tried it last week and it worked well.

Fantastic George! Can't wait to get mine back together and give it a go.

Yes get your finger out

Did a quick run of the PHD data thru Pecprep, full report in the morning.

Worm Period: 479 Secs

Steps/Period: 50133

Sample Count: 1742

Sample Int.: 0.99 Secs

Trend: Y = 0.0000X + -0.2

Peak PE+: 1.51 arcsecs

Peak PE-: -1.24 arcsecs

RMS PE: 0.42 arcsecs

MaxRate: 0.52 arcsec/S

MaxRate: 0.03 x sidereal

Av. PE+: 0.37 arcsecs

Av. PE-: -0.32 arcsecs

Max Delta+: 1.10 arcsecs

Max Delta-: -0.52 arcsecs

Av. Noise: 0.00 arcsecs

Well skies cleared again but not for long, might just get my data tonight. Looking good on the PHD graph......wow just wow, best guide graph I have ever had with my EQ6......stunned

Well someone is conspiring to deny me getting data on the belt conversion, my PC decided my QHY5 guide camera didn't exist anymore and no amount of plugging/unplugging made the guider detectable . I ended up having to reflash the EPROM on the QHY5 to get it working again and yes it had clouded over in the meantime

No data tonight then

Thats because at the time of the photos and testing I'd only done the DEC axis

Both are now done and the settings are both identical.

George,

The 12 pully that needs boring out to 5mm, when you drill it basically it removes all of the center section leaving just the main pully. My machinist was querying it but i told him just to bore it out any way.

I take it yours is fine like that?

Depending on how accurate his lathe is you should be left with 0.5 - 1mm of the insert which is steel I think.

As long as there's no runout when its on the stepper shaft you should be OK.....mine has the slightest of slight wobble Im on the lookout for a solid steel replacement which will be a doddle to bore.

First indications of my own conversion are looking very good, my PHD graphs were looking excellent compared to what I was getting but I didn't get enough data to run thru Pecprep.

I also spent a couple of hours on Sunday lapping the RA worm and wheel, I can turn the RA worm with 2 fingertips with the mount fully loaded......never been able todo that before

George,

I have a complete set of SKF bearings, very smooth, and the belt mod kit. I will take the pullies to the machinist tomorrow and start stripping the mount.

Did you need to machine out the RA in the end, to provide more belt tension?

Thanks

Neil C

No Neil, no modifications to the actual mount castings. Both stepper back plate screw slots need lengthening slightly, 2 minute job with a small round file.

Well if it all goes pearshaped then I've only wasted £30 for the parts.

George, what did you use to pull the gear off the motor shafts ?

On the stepper shaft gear there are 2 hex grubs, just loosen off and it should come easily, if not wrap something soft round it and wiggle free with grips......same with worm shaft gear.

Alternatively have a gander on Astrobabys site

BTW on the Motionco site the dimensions of all the pulleys are listed so you should be able to work out what space you have, there's room for quite a bit of material removal on the 48 tooth pulley, the dimensions I listed in the 1st post are only bare clearance measurements for the EQ6 and I could have taken a bit more off if needed.

Yes. But my thinking was that if the firmware could be suitably modified then the 4:1 change could be made *and* the handset would still function correctly.

James

Im sure some selected source code was released a while back but Im certain it was forASCOM plugins, anyway if the firmware was hackable Im sure it would have been done by now

Check the EQ6 Yahoo group.

Obviously the middle idler gear would be removed, and then the large gear on the worm spindle and the small gear on the motor will need replacing with suitable pulleys, but wondered how you go about working out the belt length and pitch of the pulleys to give the 4:1 ratio. I would like to do this mod without any (or much) re-working of the covers etc (be nice to get a drop in replacement).

Centre distance calculator

Measure from the centre of the worm wheel to the centre of the stepper shaft, put your pulley combination in the boxes , select the belt length until it matches your measured centres. Thats what I did and it was spot on.

James it will be in the firmware, using EQmod does away with the handset thereby doing away with the firmware.

very interesting. when you finish can you please post a pec curve and an image?

That's the plan, with the weather here expect it sometime next spring

I completed the RA axis belt conversion tonight and it was as straightforward as the DEC axis. Might have to elongate the RA stepper mounting plate screw holes a little with a file to get a little more belt tension, I'll see how this goes with a full mount load tomorrow.

Might have a chance of clear skies towards the end of the week

Excellent! Ordering the bits now...I hope I can get my Machinest to actually do the mods quickly rather than in six months!

You are a Star George. (Well what else would you be on an Astro Forum )

Make sure he/she centres the gears correctly in the lathe before boring, I had a slight run out on my 12 tooth gear but hopefully the belt will take this up and it shouldn't have any impact unlike on a tooth to tooth gear.

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

This modification was pre-discussed here http://stargazerslounge.com/discussions-mounts/139411-eq6-belt-mod.html

****Please note****

This modification is for NEQ6/EQ6 mounts running EQmod ONLY, the Synscan/Syntrek handsets only support Skywatchers/Syntas proprietary 3.92:1 gear ratio.

You will need access to a lathe to re-bore the gears to fit the worm and stepper motor shaft.

48 tooth gear needs re-boring to 12mm

12 tooth gear needs re-boring to 5mm

48 tooth gear needs 3mm taking off the overall width of the gear.

No modification to the mount itself is needed.

Parts List

I eventually settled on the 2.03mm pitch gears 48 & 12 tooth gears for a ratio of 4:1 because it involved no modification of the mount and minimal modification of the gears themselves.

motionco_Pulleys & Belts_Aluminium MXL Timing Pulleys_Buy Online

motionco_Pulleys & Belts_Neoprene MXL Timing Belts_Buy Online

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

If you don't have access to a lathe you can buy and have the gears modified here HPC Gears, modifications page

The following images were taken when modifying the DEC axis on my EQ6.

DEC worm housing and stepper before modification

All the parts used from the above parts list, gears have been re-bored and width reduced on the 48 tooth gear.

A before and after shot after removing the original gears, 12 tooth gear fitted on the left.

A close up of the modified DEC stepper

48 tooth gear and belt fitted to the worm prior to fitting, make sure the belt is kept free of oil & grease

No modification is needed to the mount, the gear slot comfortably takes the new 48 tooth gear and 6.35mm belt

Elastic band used for looping the belt over the stepper pulley prior to fitting

Worm housing now fitted to mount and belt is pushed thru mount slot, in a dry run before I greased everything up the elastic band worked well for looping the belt over the stepper pulley but in final fitting I had problems, eventually I used strong cotton thread which was easily snapped off when the motor was fitted.

After slackening off the steppers screws slightly it was easy to gently lever the stepper to apply tension to the belt, I ran the mount for 2 or 3 full revolutions both ways to settle everything in before checking the belt tension. With a flashlight you can see when running if the belt is tight or slack.

Finally you have to set EQmod up to use the new gear ratio's, originally you had to edit the ini file but Chris Shillito added a drop down box in EQmod setup with a number of the most popular ratio's 4:1 5:1 6:1 etc.

Make sure the Custom Mount Enabled is checked (I just noticed its not in the image)

Phew that's it

As soon as we get a clear spell I'll be testing the mount out and hopefully show improved PHD graphs. I had really bad backlash on the DEC axis which could not be adjusted out.....that has now disappeared completely with this modification oh and did I mention how quite the mount is now?

All you can hear on full slew is the steady hum of the steppers....no more transfer gear rattle and squeal

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

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

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

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.

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.

I would prefer not to have to machine anything as i only have a Dremel...which is brilliant but i do use it for stuff its not best suited to. (that would be everything)

Well Neil a bit of good news, if you use 2mm pitch pulleys instead of 2.5mm they will fit in the worm housing without any modification.

See this thread , Ive emailed Filip for confirmation and will post his answer when I get it. Carnt find any UK suppliers of toothed 2mm pitch gears so Ive priced using the supplier Filip gave in his post. Filips mod give's a 4:1 ratio which Chris has confirmed will work with EQmod.

Pictures of Filips mod

https://sdp-si.com/eStore/default.asp

Drive belt:

6R51M082060 GT2 (2mm) Pitch, 82 Teeth, 6mm Wide Neoprene Belt $4.01/Each

Stepper pulley:

6A51M012DF0603 GT (2mm) Pitch, 12 Teeth, Aluminum Alloy Timing Pulley $9.37/Each

Worm Pulley:

6A51M048DF0606 GT (2mm) Pitch, 48 Teeth, Aluminum Alloy Timing Pulley $14.13/Each

Any combination that gives a 4:1 ratio will work - it doesn't have to be a 60 tooth pully - 48 and 12 tooth perhaps ?

Thanks for that Chris , Ive just noticed on Luke Bellani's thread on ICE that he had to machine the worm housing to accept the new pulleys, I don't have access to a milling machine so gears that will fit in the housing as is will have to be used. Ive asked the question on the Yahoo EQ6 group

As a last resort an end cutter on a pillar drill would probably suffice or even a dremmel for some minor modification if you don't have a milling machine but I'd rather not go down that route.

This US site https://sdp-si.com/index.asp came in considerably cheaper but they are out of stock the 60 tooth pulley