CG5 Dec Axis Completely Stuck - Please Help!!

[bendiddley]

I have acquired a CG5 mount and the Dec axis is completely stuck solid. The gears turn but the axis cannot be turned on its own. I have obviously checked the clutch is off.  I have started disassembling the axis to see if I can free it up to clean and regrease it all and I have got as far as the central tube with the grey notches on the top (see photos). I don't know the name for this part so apologies for the lack of terminology. This is the part that is stopping the Dec axis from turning and I cant see how I can get it out. I've had a small attempt at twisting it off using a type of wrench with a tea towel between the wrench and the tube to protect the notched end of the tube but I'm worried with too much force I might damage the notches. I also tried a thick piece of rubber between the wrench and the tube and this didn't work either. My only other thought is coming in from underneath with a hammer and a screwdriver to prise the tube upwards but again I am worried about damaging the metal. I have no other ideas and am worried I won't be able to get this part out. Can anyone offer any ideas or advise on this one? Many thanks.

[spaceboy]

I would put it in a bucket of warm to hot water for 20 mins. I am aware of this happening with other EQ5 / CG5 mounts and my guess it is where the mount hasn't been used in a while and the aluminium casting have oxidised and so formed a bond between the two parts. The warm-hot water should offer up enough expansion that the parts will free from each other with the help of a little elbow grease. 

[Oddsocks]

I can't think you will get too much advice on this question, the casting is very fragile and is easily damaged, for an experienced engineer working in a well equipped workshop the task is not so difficult but I am guessing from your post this is not your situation?

The only method I can suggest that is the least likely to cause damage follows but anything you do try is at your own risk so do not attempt unless you are prepared for terminal damage!!!!!

You will need a can of penetrating oil such as PlusGas or WD40 Fast Release Penetrant (Specialist Range), available from Amazon, eBay, your local car spares shop etc:

https://www.amazon.co.uk/d/DIY-Tools/WD-40-44709-WD40-Fast-Release-Penetrant-250ml/B00KPUBO28/ref=sr_1_1?s=diy&ie=UTF8&qid=1491679789&sr=1-1&keywords=penetrating+oil

https://www.amazon.co.uk/English-Abrasives-802-10-Plusgas-Aerosol/dp/B0001P02RK/ref=sr_1_2?s=diy&ie=UTF8&qid=1491679789&sr=1-2&keywords=penetrating+oil

 

Measure the diameter of the worm gear, thats the grey bit with the "notches" that you are trying to remove, and select an appropriate "Jubilee" clip from the choice available at Amazon, eBay or your local car spares shop. The Jubilee clip you choose should have an adjustment range that covers at least 5mm smaller than the diameter of the worm gear to at least 20mm larger.

https://www.amazon.co.uk/s/ref=nb_sb_ss_c_2_7?url=search-alias%3Ddiy&field-keywords=jubilee+clips&sprefix=jubilee%2Caps%2C150&crid=1655GZ5496V6V

First step:

Remove completely the DEC lock handle, spray the penetrating oil liberally around and inside the DEC lock handle opening, around the point where the worm gear exits the DEC housing casting and around the point inside the casting where the worm gear bottoms out against the DEC housing casting. Use plenty of oil so that the casting is dripping. Leave alone for twenty four to forty eight hours and top up the penetrating oil if it shows signs of drying out.

After this soaking period is over dry off the worm gear and wrap a piece of firm rubber sheeting around the teeth of the worm gear to prevent damage, slip the jubilee clip over the rubber so that the body of the Jubilee Clip aligns with the raised casting of the DEC lock and tighten the Jubilee clip firmly to grip the rubber but do not over tighten.

Cut a small piece of timber into a wedge shape and gently tap the wedge into the gap between the raised piece of casting for the DEC lock handle and the body of the Jubilee Clip using a light "pane" hammer. You must not use excessive force or the casting will be damaged, you are just using this to provide a "splitting" force  of around 10N (equivalent to around 1Kg of weight).

Hopefully this will be enough to separate the worm gear from the casting, you can apply a little heat to the casting with a hair dryer to make it expand if it is still stuck.

If this does not work the only alternative is a visit to a well equipped workshop where they will be able to separate the worm gear from the housing with the appropriate tools.

There should be a plastic washer between the end of the worm gear and the body of casting, be careful not to lose this if/when you get the parts separated, also watch out not to lose the plastic pad fitted to the end of the DEC lock.

I've added notes to your posted pictures, I suspect my text will be as clear as mud so hopefully the pictures will explain it better.

 

 

 

[bendiddley]

Thank you both for your advice, both very helpful, I will definitely look into these. Oddsocks that is a fantastic reply and lots to get my head round and look into, can I ask firstly what is the purpose of the jubilee clip? And also you say the wedge goes into "the gap between the raised piece of casting for the DEC lock handle and the body of the Jubilee Clip",  do you mean the gap between the dec lock housing and the worm gear, from your drawing that's the only gap I can see?

[Oddsocks]

Hopefully the attached sketch will make it clear, with the Jubilee clip tightly gripping the worm gear you drive the wooden wedge into the gap between the Jubilee clip screw-housing and the square part of the DEC lock extension on the side of the DEC body casting, the red arrows show the direction of the forces applied, as you tap the wedge into the gap the worm gear will be forced out of DEC housing.

The body of the screw housing on the jubilee clip provides one fulcrum for the wooden lever to act against, the square body of the DEC lock lever extension provides the other fulcrum.

For clarity in the sketch below the wedge is shown pointing towards the DEC housing but when you do this in practice the wedge is parallel to the housing, like in the adapted photo that I posted above, it still works just the same but do not use excessive force when driving in the wedge or the DEC housing will be damaged, it is not very strong!

 

 

[bendiddley]

Ok I get it now, thanks for extra clarification, much appreciated. The only thing I'm not sure is going to work though is the jubilee clip staying put. Earlier you say not to over tighten it, but if it's not really tight isn't is going to slip upwards as the wedge is tapped in?

[Oddsocks]

The Jubilee clip won't slip provided a piece of strong, rigid, rubber strip/belt is placed between the worm gear and clip. The rubber strip/belt will dig into the grooves of the worm gear to provide grip and mould itself around the edges of the clip.

By over tightening I mean do not use so much force that the worm gear is distorted, or the grooves of the worm gear are damaged, provided the worm gear is clean and dry then a good grip will ensue. Because the leverage is on one side of the clip it will tend to twist and dig in more as you tap in the wedge.

A good soaking with penetrating oil before using the clip and wedge plus the shock of tapping the wedge should break the friction that is keeping the worm gear locked into the housing, we're not talking about using tons of force here, a kilo or two of pressure from the wedge together with the "shock" caused by tapping the wedge should do the job. 

This is a technique used in garages all the time to separate seized bearings where a conventional bearing puller would damage soft aluminium housings, you may have a local car repair workshop that can do this for you, they will probably have a selection of Jubilee clips the right size in their tool kits.

 The important thing is to use the penetrating oil first, and leave it to soak-in, to loosen the dried grease that is binding the two parts together, the Jubille clip and wedge just provides enough force to pry the two apart.

If you do decide to try the Jubilee clip make sure it is a good quality clip, not the light- short bodied type used for air conditioning ducting but the strong clips used for high pressure hoses, these are the ones you would find used in a garage. 

[bendiddley]

That's great, thanks so much! I will go and buy the oil and jubilee clip and let you know how I get on.

[Oddsocks]

For the rubber strip, cut a piece of worn out bicycle tyre carcass, you can find plenty for free at your local recycling centre or bicycle shop.

You may well find that a day or two soak in penetrating oil will do the job without resorting to the jubilee clip anyway, just a few gentle taps with a wooden or plastic mallet may shock the parts free and allow you to twist the worm gear out of the housing.

Best of luck anyway....

By the way, have you looked at the CG5 mount guide pages on the Astronomyboy site?

http://www.astronomyboy.com/cg5/

[bendiddley]

Thanks, I was going to use some left over rubber that was used on our garage roof, it's about 2mm thick, is that thick enough? There's a bike shop round the corner from me I could go and ask for an old tyre if they have one, you think that would work better? Regards tapping it after the soak, where about would I tap it? Thanks for the astronomy boy link, yes I've been using that tutorial to dismantle the Dec axis, has been very helpful. 

[Oddsocks]

1 hour ago, bendiddley said:

I was going to use some left over rubber that was used on our garage roof, it's about 2mm thick, is that thick enough?

Yes, roofing rubber will be fine.

 

1 hour ago, bendiddley said:

Regards tapping it after the soak, where about would I tap it?

Tap it directly on the end of the worm gear as if you were trying to drive it further in towards the housing. The force of the tap is used to "shock" the worm gear into breaking free, not physically drive it any further in so you don't use a heavy hammer with mass but use a carpenters wooden or plastic mallet or even a bulk of wood, a rubber mallet would not work. You use about the same force as if you were going to knock loudly on somebody's front door with your knuckles.

[spaceboy]

19 hours ago, spaceboy said:

I am aware of this happening with other EQ5 / CG5 mounts and my guess it is where the mount hasn't been used in a while and the aluminium casting have oxidised and so formed a bond between the two parts.

This was another case of a CG5 seized worm gear only this time it was on the DEC axis the problem arose. Not sure if there is anything in the thread that may help with your issues but maybe worth a read through all the same ....

 

[bendiddley]

3 hours ago, Oddsocks said:

Yes, roofing rubber will be fine.

 

Tap it directly on the end of the worm gear as if you were trying to drive it further in towards the housing. The force of the tap is used to "shock" the worm gear into breaking free, not physically drive it any further in so you don't use a heavy hammer with mass but use a carpenters wooden or plastic mallet or even a bulk of wood, a rubber mallet would not work. You use about the same force as if you were going to knock loudly on somebody's front door with your knuckles.

Great thanks.

[bendiddley]

3 hours ago, spaceboy said:

This was another case of a CG5 seized worm gear only this time it was on the DEC axis the problem arose. Not sure if there is anything in the thread that may help with your issues but maybe worth a read through all the same ....

 

Thanks Spaceboy. Interesting post, slightly different to mine in that his worm gear came out but was still attached to the dec shaft. My dec gear is wedged inside the dec lock housing so needs a different solution to get it out. I'm going to give oddsockss trick a go and see if that works.

[triton1]

I posted some time ago I had the exactly the same problem with my Dec axis on my Cg5 when I bought mine.I put the worm wheel in a vice with two lolly sticks each side to protect the thread(grooves) and then heated the housing up with my missus hairdryer for about 15 mins gave it a sharp twist and pull at the same time and hit myself in the face.Felt abit of a numpty but job done.I think it's the grease that's been used it goes off like glue.

[bendiddley]

19 hours ago, triton1 said:

I posted some time ago I had the exactly the same problem with my Dec axis on my Cg5 when I bought mine.I put the worm wheel in a vice with two lolly sticks each side to protect the thread(grooves) and then heated the housing up with my missus hairdryer for about 15 mins gave it a sharp twist and pull at the same time and hit myself in the face.Felt abit of a numpty but job done.I think it's the grease that's been used it goes off like glue.

Thanks John. Unfortunately I don't have a vice, but I have a solution from Oddsocks which I'm going to try.

[bendiddley]

On 08/04/2017 at 21:42, Oddsocks said:

Measure the diameter of the worm gear, thats the grey bit with the "notches" that you are trying to remove, and select an appropriate "Jubilee" clip from the choice available at Amazon, eBay or your local car spares shop. The Jubilee clip you choose should have an adjustment range that covers at least 5mm smaller than the diameter of the worm gear to at least 20mm larger.

I've found a jubilee clip on eBay which is 70-90mm. My worm gear is 74mm, so the clip is slightly smaller than what you are recommending above, is that going to be OK? Also what do you think of the clips...

http://www.ebay.co.uk/itm/Jubilee-Clips-Genuine-Jubilee-hose-clip-Fuel-hose-pipe-clamp-worm-drive-Steel/281955639394?rt=nc&_soffid=5026634306&_soffType=OrderSubTotalOffer&_trksid=p5731.m3795

Or this one on Halfords..

http://www.halfords.com/workshop-tools/garage-equipment/fuses-electricals-fixings/halfords-hose-clip-70-90mm

[Oddsocks]

The size 70mm-90mm should be fine, if you find it will not clamp up fully tight with the off cut from the rubber roofing material then resort to the old bicycle tyre for the rubber strip as it will be thicker and increase the diameter to around 80mm. The rubber roofing material won't work if you try doubling it up, it just slips over itself, the rubber strip has to be a single thickness to work properly.

The Halfords clip looks like it should be ok but I find Halfords web site frustrating, is the Jubilee Clip made of plated steel or aluminium? Aluminium is too weak and will stretch and stainless steel is too brittle for this type of job, also find Halfords rather expensive.

Linked below is a plated steel 70mm-90mm Jubilee Clip, Kite Marked, and half the price of the Halfords one with free delivery thrown in (although that'll be second class post so probably end of next week by the time Easter hols is out of the way). If you want the Halfords one then suggest you wander off to the local store with a magnet and just check it is steel before you buy it (though the in-store staff should be able to confirm if it is steel or otherwise)

https://www.amazon.co.uk/Jubilee-Zinc-Plated-Hose-Clip/dp/B004J32P3E/ref=sr_1_4?ie=UTF8&qid=1491911975&sr=8-4&keywords=jubilee+clips+70mm+-+90mm

The other site you linked to is in the US, can't think you would want one from there, import duties and two week minimum shipping time....

 

[bendiddley]

22 minutes ago, Oddsocks said:

The size 70mm-90mm should be fine, if you find it will not clamp up fully tight with the off cut from the rubber roofing material then resort to the old bicycle tyre for the rubber strip as it will be thicker and increase the diameter to around 80mm. The rubber roofing material won't work if you try doubling it up, it just slips over itself, the rubber strip has to be a single thickness to work properly.

The Halfords clip looks like it should be ok but I find Halfords web site frustrating, is the Jubilee Clip made of plated steel or aluminium? Aluminium is too weak and will stretch and stainless steel is too brittle for this type of job, also find Halfords rather expensive.

Linked below is a plated steel 70mm-90mm Jubilee Clip, Kite Marked, and half the price of the Halfords one with free delivery thrown in (although that'll be second class post so probably end of next week by the time Easter hols is out of the way). If you want the Halfords one then suggest you wander off to the local store with a magnet and just check it is steel before you buy it (though the in-store staff should be able to confirm if it is steel or otherwise)

https://www.amazon.co.uk/Jubilee-Zinc-Plated-Hose-Clip/dp/B004J32P3E/ref=sr_1_4?ie=UTF8&qid=1491911975&sr=8-4&keywords=jubilee+clips+70mm+-+90mm

The other site you linked to is in the US, can't think you would want one from there, import duties and two week minimum shipping time....

 

Thanks! I've ordered the amazon one, good find! And thanks for the tip re rubber/tightness, hopefully it will be tight enough but if not I'll see if I can get a bike tyre.

[Oddsocks]

32 minutes ago, Oddsocks said:

The other site you linked to is in the US, can't think you would want one from there, import duties and two week minimum shipping time....

Interesting, never noticed that before in Stargazers Lounge forum but if you copy and paste the link you provided to the eBay UK site in a new browser window it goes direct to the UK page, if however you click on the link directly in the forum post it goes to somewhere else called Viglink.Com and from there to the USA eBay site....how odd..?

[bendiddley]

When I just opened my eBay link it went straight to the UK eBay page that I got it from and I checked and it said is was from Brighouse, united kingdom (didn't think I'd left 'united kingdom only' unchecked), anyway it doesn't matter, your amazon one was cheaper!

[bendiddley]

Great news! I managed to free the worm gear from the casing. It needed quite a few bangs on the wedge with a hammer and I had to secure the whole thing in my work bench before it would start to work but I got it out in the end. Since cleaning it all up and regreasing although it now turns it is unfortunately still quite stiff. I can tell where the stiffness happens. As I insert the worm gear into the housing when it is up to 2/3 of the way in it turns very easily but when you push it in all the way it suddenly becomes stiff again. I'm not sure what is causing it, does it need a different kind of grease or is the housing just to tight,  I don't know. I am using the brown Geoptik grease which I bought from Rothervalley Optics, its meant to be the proper stuff, seems to work well on everything else. Is there anything else I can try?

[Oddsocks]

Stiffness at the two thirds insertion distance would tally with the locking clutch position and suggests that a previous owner may have overtightened the clutch at some time distorting the hub or the housing.

The way to remedy this would be to completely clean off all the grease from the worm-hub and housing with solvent and detergent then rub a thin layer of a special ink paste called " Engineers Blue" or sometimes "Micrometer Blue" over the worm-hub and over the walls of the housing, you carefully push the worm hub back into the housing all the way in and turn it a few times in each direction. Then remove the worm hub but try not to turn it while doing so, or if necessary just "wiggle" it a bit from side to side until it is out.

Now look at the ink, where the hub or the housing has high points and is binding the ink paste will have worn away revealing the bright metal below, where the two parts have a big clearance the ink remains in place and looks dark blue.

How to interpret the results?

1:   A high point (or several) on the housing will look like an isolated bright patch while the rest of the housing will look dark blue, at the same time there will be a "ring" of brightness right around the worm-hub.

Remedy:

First use the coarsest grade of Wet and Dry paper (~180 grade) to rough up the high point(s) in the housing so you can find them again, then clean off the Engineers Blue so the housing is dry and continue to rub down the high point(s) with ~320 grade grit and ~400 grade grit Wet and Dry paper. Thoroughly clean the housing so no grit remains, apply a little grease and see whether you have removed enough material to ease the binding, if not, wipe away the grease and apply more Engineers Blue, test and assess then repeat the Wet and Dry until you removed the stiffness.

2:   A high point (or several) on the worm-hub will look like an isolated bright patch while the rest of the worm-hub will look dark blue, at the same time there will be a "ring" of brightness right around the housing.

Remedy:

First use the coarsest grade of Wet and Dry paper (~180 grade) to rough up the high point(s) on the worm-hub so you can find them again, then clean off the Engineers Blue so the worm-hub is dry and continue to rub down the high point(s) with ~320 grade grit and ~400 grade grit Wet and Dry paper. Thoroughly clean the worm-hub so no grit remains, apply a little normal grease and see whether you have removed enough material to ease the binding, if not, wipe away the grease and apply more Engineers Blue, test and assess then repeat the Wet and Dry until you removed the stiffness. Make sure to clean the grooves of the worm gear with a tooth brush dipped in solvent, paraffin, penetrating oil etc to remove any trace of grit that may remain.

3:    If the worm-hub or housing have no individual high points but rather the worm-hub or housing are not machined accurately you may find that there is a ring of brightness around both parts, in this case you need to rub down whichever is going to be easiest, probably the worm-hub, and to do this use strips of ~320 grade grit and ~400 grade grit Wet and Dry paper pulled back and forward around 180 degrees of the cylinder as if you were towelling your back after a shower, after every half a dozen pulls of the Wet and Dry paper turn the worm-hub 45 degrees so that the abrading is spread evenly around the worm-hub.

Once all stiffness is removed, and this will take a few hours of work, any grease or ink paste is removed for the last time, fresh grease applied and the hub and housing reassembled.

I have linked to a tin of Engineers Blue and a pack of Wet and Dry below, if the forum software redirects you elsewhere then copy and paste the link into a new browser window.

Both items are available on other market place sites at various prices, I didn't  search for the cheapest these are just to let you know what to look for.

P.S. get a box of disposable gloves when handling the Engineers Blue paste otherwise you will end up with blue hands and to clean off the Engineers Blue you need Methylated Spirits from any DIY store.

http://www.ebay.co.uk/itm/Stuarts-micrometer-engineers-marking-blue-tin-1s-4-35-3s-4-00-5s-3-60-each/252034989081?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D40656%26meid%3D3bd8e0cc4d504322b3dbe8af8ffc4503%26pid%3D100005%26rk%3D2%26rkt%3D6%26mehot%3Dpp%26sd%3D162425914923

http://www.ebay.co.uk/itm/12-x-Assorted-Flexible-Wet-Dry-Sandpaper-Fine-Medium-and-Coarse-/282437345047?hash=item41c293df17:g:cY0AAOSwOyJX6DFy

[bendiddley]

Wow! Another great solution again, thank you so much, would never have thought of this. I will go and buy those items today. Thanks again odd socks! The end is in sight again, hopefully!