EQ5 Belt and Pulley mod

I have seen snippets in places for an EQ5 pulley mod but I have seen nothing that will give the

complete information on what is needed or how to do it with what is involved.

So this belt mod is for an EQ5 Pro and the same can be applied to the upgrade version.

To some this mount is getting old, but if this mount is all you got and you can make it better then

why not.

If after doing this you get the urge to improve on my attempt and this has helped in that direction

then be like me and post it for people to use for free.

Also if you see any glaringly obvious idiotic mistakes then please let me know so I can correct them.

Please read the whole thing before starting, In case you get caught out with needing something

unexpected.

This does not affect the ratio if you still use your handset. I use this setup in EQmod and going from

cogs to pulley nothing was changed in the Ratio setup either.

Having some sort of DIY skill would be a bonus.

I assume this could affect your warranty if you still have one, so make your choice, ask your mum ,

draw straws or just rip up your receipt.

And like all things this has a disclaimer too. I am not responsible if your mount blows up, your shed

blows up or even if your granny blows up. Though if any of this happens send me pictures cos it

would be funny.

All links for the parts will be at the bottom, Just to make you scroll down really.

If you plan on stripping the whole mount down and do a clean and a re-grease this could be a good

time to do this too.

A side note to this is I did strip mine and used the dremel buffing attachment and polished ALL the

aluminium parts, This makes a huge improvement especially with using quality grease.

Popular opinion on grease is superlube (not to be confused with that stuff your wife gets from Anne

Summers) for the interior aluminium sliding parts and it is good stuff too, used sparingly. And for the

worm gear and RA/DEC teeth a stickier grease is better as It won’t be so easily compressed off the

teeth and has more chance of staying in place which not only helps as a buffer between the teeth it

obviously will cut down wear on the worm gear.

Admittedly some of the photos could be better. But when you are physically doing this it will be

apparent of what to do. There are not that many parts to mess with even if it looks that way.

Tools I used were:

Stanley blade

Portable drill, don’t need anything hefty.

Drill bits. 7mm 6mm 5mm 4mm for metal if using Aluminium, but wood ones might be ok for the

Perspex.

Pinion gear remover. (I made my own but I will link one for you)

Posi (cross head) screw drivers.

Metric hex (Allen) key set. Ranging from 0.5 upwards. Though at a guess you would never need one

bigger than 7mm.

Dremel and a grinder. This will become apparent but you can get away with just a dremel.

Some Loctite for bolt threads or something similar. If you think superglue is a good idea, Think

again.

Items I needed:

Small aluminium sheet or Perspex , Either will be strong enough for making the idler mount. This was

5 mm thick and no more than 4inches square is needed as that is ample. Unless you mess up so

more is better.

Wardrobe/cabinet bolts (the ones that screw into each other).

These come in pairs and you will need two pair for the idler mount and another two pair for holding

it in place, Though only the outer bolt is needed for that part.

4 flange bearings

2 large pulleys

2 small pulleys

2 belts.

3 Rubber washers or similar.

Tea and cake from my wife. Thanks Sharon. Though you lot won’t be getting any unless you are at

my house and I’m doing this for you. But then I will be getting paid for working so win for me.

Firstly I separated the RA from the DEC by removing the two side bolts which makes working with

each part easier.

It might even be worth removing the polar scope and altitude bolts so they don’t get in the way. I

did.

You can mark the orientation with tape on the two parts so they go back the same way if you wish.

Take off the plastic cover on the end of the DEC motor, 2 screws.

Remove the motor from the DEC which is only held in place by one hex bolt with a spring washer

and a normal washer (which is crap and could be replaced with one a bit stronger)

Using a Hex key remove the cog that is attached to the motor mount (two hex bolts on the side and

that’ll be the middle cog on the next picture). Bag the cog for safe keeping and keep the three little

washers handy.(They are stuck together with grease). Leave the two hex bolts in the motor mount,

you will still need them.

Remove the two screws that hold the plastic cover on the motor, gently slide the cover back and

unplug the connector from the back of the motor. Putting this back is a pain in the ass as the wires

are quite stiff and get forced on the back of the motor. If this is the case for you as it was for me.

Remove the two screws that hold the DEC socket on the back and slide the socket out a little way.

When you plug the connector back on slide the cover over the motor and put the two screws in for

that. Then gently tease the rear DEC connector socket back in its hole and put the two screws back in

also. I also covered the wire side of the socket with insulating tape as I didn’t like the idea of bare

connectors so close to the rear of the motor. Note the RA motor has no cover.

Here is the motor with the plastic cover on.

Unscrew the 3 hex bolts to remove the motor bracket from the motor. Note the orientation so you

put it back the same way

I did find the EQ5GT sticker interesting and amusing considering the mount that came up on a

search. Anyway onwards eh!

While the motor is off now use the Pinion gear remover to pop the little cog off. If you use anything

but one of these. IE: leverage with a screwdriver or a similar way you WILL bend the motor shaft as

they are not that strong.

This can be a little tight, Just take your time in applying the pressure and it will pop right off

Getting your little bag of goodies ready you now need to put the small 9 tooth cog on to the motor

now that the cog is off.

This bit can be a bit fiddly as you want to slide it on and tighten so the grub screw is just slightly

above the motor bracket when it is fitted. A good idea is to slide it on and slightly nip the grub screw

so you can still slide it while holding the bracket in place so you get an idea of where the screw is.

This is then about the right place for it to line up with the main pulley on the Worm gear.

You now need to refit the motor bracket with the 3 hex bolts. (Make sure it’s fitted the correct way).

Now remove the worm gear from the mount and remove the brass cog and pop it in your save bag.

This now needs a little bit shaved off one of the mounting lugs as the large pulley will catch on it.

Also the hex bolt on the same side of the pulley will need trimmed so it does not protrude into the

pulley belt.

I wrapped the whole thing in a rag so just that lug was showing. But if you want you can always strip

the whole thing and do it with nothing fitted.

This is where you will use a Dremel or even a grinder if you are careful.

I removed just about 1/8th of an inch. Take your time as anything you trim off can’t be put back on.

Do a bit and check it , repeat until you are happy with the clearance. This includes the belt sitting on

the pulley. The metal is fairly hard so you won’t be surprised by a shit load coming off at once.

This enlarged photo shows how much I will take off downwards and how far back, It is just a small

square area, Also the hex bolt in this position will have the right amount reduced too.

This is trimmed and painted white just so you can see the small clearance as you only need to

remove enough to be clear.

Now you have that trimmed and you have fitted your large pulley. You can refit the worm gear with

the pulley back onto the mount and adjust for play Ect (make sure you put the short trimmed hex

bolt through the correct mounting lug). So adjust like you would normally, You might even find

when using the pulley wheel to turn the axis it seems quite easy. Either way do your adjusting until

you are happy of no binding and it is free to move.

Now you will need the Perspex or aluminium piece to make the holder for the idler. Here is the

shape I made and also a couple of photos of the top and bottom so you can get the idea of what it

looks like. You could print this off and scale it so it fits then use it as a template to make your own.

Or even design your own. As long as it holds the idler in the correct place and tensions the belt it will

work.

Top.

Bottom.

And the drill bit sizes

You should now end up with two of these exactly the same, One for each motor bracket.

Now for the actual idler. The wardrobe/cabinet bolt will need cut as it is far too big.

And this needs to be done on both parts, the threaded part needs cut so it is just proud of the plate

face. The other one needs to be cut too so the washers; flange bearings and rubber washer make up

the length.

This shows the original length and also what it needs to be cut too (8 threads showing), Also the

head will need filing or Dremeled down to fit into the countersunk hole on the bottom.

When the small bolt is in the recess on the bottom it will be short but perfectly usable

Once this is done get your 3 washers you saved from before and slide one on to the hollow bolt

shaft. Then put the two flange bearings facing opposite to each other as shown. Then the other two

washers and lastly for packing the small rubber washer so it looks like this.

Doing this will also show you the length this bolt needs to be as it stops short just inside the bottom

edge of the rubber washer. If you make it too short you will compress the parts and flange bearing

will be stiff. If that’s the case the top washer could be taken out to free them up and also keep the

bearing at the right height. Or put your glasses on and cut another bolt.

Push the short bolt through the bottom and apply some Loctite or similar then screw the part you

just assembled onto the top it should now look like this.

The top hole will fit over the hex bolt on the motor mount and the hole nearest to the idler will have

a short bolt (the spare cabinet outer bolt cut to length) pushed in and tightened in place with the

two side hex bolts just like the original cog was. You can trim the side of the rubber washer to get

better access, I also trimmed the other rubber washer in half so I had two thin washers then cut it in

half across so it fitted next to it so when I pushed the bolt in it would press down on some rubber

and spring press the idler plate.

The plate will still have slight movement when fitted but it will stay in place by the hex bolt at one

end and the bolt pushed in next to the idler and that is all it needs .

As you can see they are identical for both motors.

And here you can see I have pushed a short bolt into that hole with a piece of rubber as a washer.

If you have spare wardrobe/cabinet bolts (x2 one for each motor) you could use one of them. Just

trim it to length so it drops in that hole. As long as it fits and flatter the head the better.

If the short bolt you use is too near or catches the large pulley just trim the top of it so it is flatter.

Note: This photo makes the pulleys look wonky but the motor has not been adjusted nor tightened

up yet.

Now the time has come to fit the motor back on to the mount. Put the bolt with washers through

and screw into the motor mount but not tight yet. Slide the belt over the small pulley and then ease

it over the larger pulley. Hopefully it will all be in line and the belt will be leaning into the idler

between the flanges. Making sure the belt has tension, but no too tight and that the motor pulley is

parallel to the large pulley tighten the hex motor bolt and check the tension again. If too tight or too

slack just redo that bit until you are happy with it. It should now look like this.

(Note: The idler bracket on this photo is slightly larger than others; this was my first test run and is

now trimmed off to make it tidier. The Paper template is also the new shape.)

Notice how parallel the pulleys are, Adjust until yours is the same you don’t want it running out.

Well that’s one done you can paint the face of the large pulley, I did just so I know it is revolving and

that the worm shaft was not slipping inside. Any sort of acrylic will do just make sure it is clean of

manufacturing oil. Also if you ever need to clean the pulley teeth of debris over time just use an old

toothbrush.

The RA is more or less the same scenario, Take out the 3 screws from the plastic cover. Remove the

plastic cover with no socket which just comes away easily, and the side which has the socket can be

moved slightly to one side and gently unplug the two wire connectors, they only go back one way so

no confusion there.

Remove the motor from the mount. The bolt hole is up through the bottom near to where the polar

scope goes. A long hex key is good for this one.

Now do exactly the same thing with this motor as you did with the DEC motor, there is no difference

at all. Apart from the fact it has no cover and you just need to remove the motor bracket.

When you remove the worm gear you will have to trim down the lug on that one too just like the

first one.

When all that is done the next part is a little fiddly. You have to trim the mount slightly so the large

pulley does not hit it.

Only a small trim just enough to allow the pulley and belt to clear, and then whiten like this.

Don’t forget to adjust your worm gear backlash when you have refitted it.

The amount taken off on here looks large but in fact it is quite small because of the close-up photo.

Once done refit the motor and belt the same way as the DEC adjusting until it is tensioned but not

too much, don’t want to strain the motor bearing. The belt should have slight flex on the long

straight side of the belt.

All the stuff you have removed from the motors should now be in a bag like this.

And your mount should look like this.

The Dec plastic cover won’t fit back on as the pulley is too big,

The other plastic part that does not fit is the side panel where the RA motor is. This will need to be

trimmed to fit back on so you can screw the two halves back together.

I have a plan to make the cogs more sealed/covered but at the moment it’s not something I have

done.

I stuck masking tape over the plastic side just to have something to draw on with a pen. So just

holding the plastic cover against the pulley side you can work out where to draw lines that you need

to cut out with the dremel.

Here is mine so you have an idea.

Once that is cut and it fits. Re-assemble the covers taking care with the connectors and then bolt the

DEC back onto the RA.

Put it all back on your mount and plug it in and give it a good testing.

Some simple sums. 144 teeth on the RA and DEC. ratio of the mount manufactured is 704:1

We have a 9 tooth pulley and a 44 tooth pulley.

So 144 / 9 * 44 = 704…Perfect.

No cogs, only backlash left is now in the worm gear. Reduce that to absolute minimum with no

binding and you will be pleased.

This was my very first test run with guiding.

I am now on a plan to change the RA bearing to a taper roller, and change the bottom RA bearing to

something with a tighter fit as the one in there is sloppy.

Also the DEC has no bearings at all so your spinning is done on plastic washers (what a great idea).

I am going to see if there is a way of fitting needle roller bearing s into the DEC shaft.

Then it will be more efficient and even carry extra weight.

If I can do this without specialised tools there will be a tutorial for that too. Although if I have to use

a lathe or do some milling I might still do one in case people can get access at an engineer’s shop and

get someone to do it for them. Everything has a price

Wardrobe/cabinet bolts and rubber washers are from B&Q

http://www.diy.com/departments/it-solutions-cabinet-connector-bolts-pack-of-

20/37710_BQ.prd?ecamp=Seapla&ppc_type=shopping&ds_kids=92700014019562543&gclid=CIPdk9

fe8c8CFdUy0wod_eUNOA&dclid=CKuzodfe8c8CFSqr7QodxSELwg

Rubber washers similar to these.

http://www.diy.com/departments/plumbsure-rubber-tap-washer-thread3/8-pack-of-

4/184676_BQ.prd

9 tooth pulley is from Rowan Engineering, These are the pulleys that are used on the HEQ5

You will need two and I was quoted £15 each. Plus postage. But this can change.

So if you email them or even ring they will sort that out for you. Just make sure to say you only need

the two 9 tooth pulleys.

http://www.rowanengineering.com/contact.htm

They also sell the Pinion gear puller you can see on this page.

http://www.rowanastronomy.com/productsa1.htm

The other pulleys and belt came from

http://www.beltingonline.com/

http://www.beltingonline.com/contact-us

If you ring and quote from below then you will be sure to get the same as mine. Unless they mess

the order up.

Just to reiterate for these pulleys, you don’t need the bore modified you only need the modification

of 2 grub screws on each pulley. So make sure they know that.

2 x 44 Tooth T2.5 Pulley (part number 4890)

Bore is 6mm

Grubscrew Holes x 2 M2 which is a 0.5 hex key. If you want larger ask them.

2 x T2.5 Synchroflex® Timing Belts (part number 2903)

Width in mm=6mm

Belt Length in mm=145mm

Tension Cords=steel no stretch

Material Standard= PU

The flange bearings are from ebay.

This size and you need x4 BEARING SIZE: MF105ZZ 5MM X 10MM X 4MM WF105ZZ

Choose the right one from the drop down link.

http://www.ebay.co.uk/itm/200709759794?_trksid=p2057872.m2749.l2648&var=500047345427&s

sPageName=STRK%3AMEBIDX%3AIT

And lastly my email to nag me on.

Any questions I will answer as quickly as I can.

Martynjdouglas@hotmail.co.uk

I have no copyright on this nor do I intend to copyright it. Also I have not or will not charge for any of

this information. It is free for anyone in the public domain and whoever wants to use it.

If anyone charges for this information then me and me dog will look into that.

As long as I get some credit for this I’m happy.

Marty.