Bearings for HEQ5 Pro

[teoria_del_big_bang]

With the recent poor viewing I have decided to strip down my HEQ5 pro mount and upgrade the bearings and add the Rowan belt modification.

From threads I have looked at on this forum and also looking at the Astrobaby guide I think I need the following bearings, I know many on here have already upgraded the bearings so thought I would just check they are correct before ordering.

 

I have ordered rubber seals in order to prevent moisture ingress. Now I know these tend to make them run slightly tighter than metal seals but they do not run at speed so though they would be better. Any thoughts?

 

Steve

Edited January 24, 2019 by teoria_del_big_bang

[teoria_del_big_bang]

Without spending too much more is there anything else I should be attending to to improve the mount?

Steve

[Skipper Billy]

Good quality grease - I used 'Superlube' and it worked brilliantly even at very low temperatures.

[vlaiv]

I can't remember exactly, but you list does look right - there are three distinct types: small ones that go on worm shaft, large ones that go on main shafts (RA and DEC) and conical one that goes on dec where CW shaft extends.

I just took mine with me, went to local shop - showed them to the guy and said "I want the best ones like these" - he gave me bunch of SKFs

Further "mods" that you could consider would be better tripod (if not pier mounted) and saddle plate.

There is one "trick" you might want to try also - but involves just settings. DEC axis can have different amounts of backlash depending where on "circle" you are checking - and if you remove backlash where there is plenty - you will get stiff motion on opposite side. If you adjust where is little backlash you might still get some backlash on other side. If this happens - you can actually determine range of DEC motion that you are likely to use with your mount - you are likely to go below equator on south side, but you are not likely to hit anything close to horizon on north side, so it is likely that DEC won't do full 360 rotation in use (it might do even less if part of sky is not accessible from your location). Place problematic part of DEC where it will not be used by turning it either by hand (worm wheel when mount motor cover is off) or in EQMod - by slewing to that position and then resetting motor position to home (not parking to home but resetting to home - if you have done PEC, make sure you don't do slew in RA - keep it as is - in home position). Return scope to home by undoing clutches.

[wxsatuser]

Looks about right to me, don't see any problem with rubber sealed bearings.

Don't over tighten the taper rollers, they should run smooth with no play when you rock or pull on the shaft.
Watch the endfloat on the tiny worm bearings, again run smooth with no pinching and no rock in the shaft.
Take your time adjusting the backlash in each worm

Some of the old 6006 bearings on mine were really rough from new, glad I did the overhaul.

It's a great mount when the bearings are done and the Rowan mod is complete.
 

Edited January 25, 2019 by wxsatuser

[teoria_del_big_bang]

Thanks for all the help and other advice (much appreciated).

I am pretty confident now I have the correct bearings and will order today. 

All in all cost me about £56 for good quality bearings. I think that is a small price to pay. I have some "SuperLube" for the roller bearings and anything else that needs it, the others bearings are greased for life and sealed so should be okay

Will be ordering all but the smaller ones for the worm shaft from www.bearingsrus.co.uk as they were far cheaper than others I found, postage was extra but under £2, and still SKF and Timken for the tapered rollers.

The smaller ones for some reason were cheaper from simplybearings.co.uk and free postage.

The Rowan belt mod will be ordered from FLO of course.

Good point @vlaiv but I hope to at least get a pier built this year if not a small obsy (usually my plans for the year take several though so not holding my breath ? )

 

Hopefully then I have a good platform for imaging, pity I can't fix the weather in the UK so easily ? 

Steve

[matt_baker]

Sorry about bringing this thread back but I was wondering which bearings are the best to replace. My guess is the small worm gear bearings rather than the large axis ones? Trying not to spend too much. Ordered some WD-40 Degreaser and Superlube from Amazon already with the intent of stripping down and regreasing. I'm thinking of jusst replacing the smaller worm gear bearings and then re greasing the larger ones rather than replacing since they cost too much and don't add much to the performance?

Matt

[vlaiv]

7 minutes ago, matt_baker said:

Sorry about bringing this thread back but I was wondering which bearings are the best to replace. My guess is the small worm gear bearings rather than the large axis ones? Trying not to spend too much. Ordered some WD-40 Degreaser and Superlube from Amazon already with the intent of stripping down and regreasing. I'm thinking of jusst replacing the smaller worm gear bearings and then re greasing the larger ones rather than replacing since they cost too much and don't add much to the performance?

Matt

How much would be too much?

If I remember correctly, I spent total of ~ £30 on all replacement bearings. All of them high quality SKF ones.

[matt_baker]

What website did you purchase them from?

[vlaiv]

1 minute ago, matt_baker said:

What website did you purchase them from?

I did not do it online - just went to local hardware store that specializes in bearings and took samples with me.

I specified that I need the best / the smoothest ones of each (low RPM but smooth operation) and the guy said - these are the best regardless of use and gave me SKF large ones and I can't remember the make of rest.

I think that it totaled less than €40 at the time (this was 4 years ago).

[matt_baker]

I think what I might do is order the smaller bearings and regrease everything in the process, then if the 6006 larger bearings are a problem, placing an order for those

[vlaiv]

3 minutes ago, matt_baker said:

I think what I might do is order the smaller bearings and regrease everything in the process, then if the 6006 larger bearings are a problem, placing an order for those

Probably best course of action. Small bearings will have the most impact on tracking performance because they turn the fastest - one turn per 638s.

[matt_baker]

Do the tapered bearings have much impact on performance?

[teoria_del_big_bang]

If you are not wanting to spend too much I would look at them first and see if they need replacing. I bought my HEQ5 2nd hand and I do not know whether the previous owner had already replaced them but in my opinion when I striped it all down it did not need any replacing, maybe the smaller bearings on the worm gear shafts, but others were fine.

I had already bought them so replaced them anyway. But, I cannot say whether they were the original ones or not as they were already good quality bearings in there.

In general these bearings are not doing any amount of work, they are not moving at 1000's rpm and have very little load on them. I think what matters is they have not been running without some lubrication at any stage and they are not over packed with thick grease. On top of that it is more the adjustments to remove any backlash both in the taper bearings and in the mesh between the worm and the worm gear.

But some gentle adjusting and most of all patience is required to get the best out of your mount.

Whilst a very good mount for the price in my opinion (and I am an engineer although semi-retired now 🙂 )  it is not exactly a piece of precise engineering so unless you are very lucky and have a perfect one I suspect you will not get rid of all backlash. I also suspect they vary from mount to mount and some will be slightly better than others but all should be fine.

The taper bearings need to be tightened just enough to take up any play but no more, from what I remember it is not much more than hand tight. If you start to put any amount of pre-;load on them then the stepper motors can stall during a fast slew to target.

On top of that there is a bit of very fine adjustment required to get the least backlash out of the worm and worm gears. If like mine they will be a bit cyclic and at some point in one rev of the gear it will have a bit more backlash than at 180 degrees different and so you can only fully remove the backlash at the tightest point and there will be minimal backlash 180 degrees away from that but there will be some. If you try to remove backlash from the tight spot then again it will bind when doing any fast slew and may show up in the guide logs.

It took me quite a few attempts to get this nominal and required some very small adjustment moving the adjustment screws just a few degrees, no moving 1/4 turn or even 1/8 turn.  

Steve

 

[teoria_del_big_bang]

I would agree with your suggested course of action in your last post.

I would suggest to remove all traces of old grease and especially if the grease in them looks in anyway contaminated.

When cleaned before replacing them in the mount just rotate them by hand, they just need to be smooth and not notchy in any way. If they are then the will need replacing.

Do not be tempted to pack them tight with grease worse thing you can do apart from leaving them dry. Just lightly pack them. 

Steve

 

[matt_baker]

6 minutes ago, teoria_del_big_bang said:

If you are not wanting to spend too much I would look at them first and see if they need replacing. I bought my HEQ5 2nd hand and I do not know whether the previous owner had already replaced them but in my opinion when I striped it all down it did not need any replacing, maybe the smaller bearings on the worm gear shafts, but others were fine.

I had already bought them so replaced them anyway. But, I cannot say whether they were the original ones or not as they were already good quality bearings in there.

In general these bearings are not doing any amount of work, they are not moving at 1000's rpm and have very little load on them. I think what matters is they have not been running without some lubrication at any stage and they are not over packed with thick grease. On top of that it is more the adjustments to remove any backlash both in the taper bearings and in the mesh between the worm and the worm gear.

But some gentle adjusting and most of all patience is required to get the best out of your mount.

Whilst a very good mount for the price in my opinion (and I am an engineer although semi-retired now 🙂 )  it is not exactly a piece of precise engineering so unless you are very lucky and have a perfect one I suspect you will not get rid of all backlash. I also suspect they vary from mount to mount and some will be slightly better than others but all should be fine.

The taper bearings need to be tightened just enough to take up any play but no more, from what I remember it is not much more than hand tight. If you start to put any amount of pre-;load on them then the stepper motors can stall during a fast slew to target.

On top of that there is a bit of very fine adjustment required to get the least backlash out of the worm and worm gears. If like mine they will be a bit cyclic and at some point in one rev of the gear it will have a bit more backlash than at 180 degrees different and so you can only fully remove the backlash at the tightest point and there will be minimal backlash 180 degrees away from that but there will be some. If you try to remove backlash from the tight spot then again it will bind when doing any fast slew and may show up in the guide logs.

It took me quite a few attempts to get this nominal and required some very small adjustment moving the adjustment screws just a few degrees, no moving 1/4 turn or even 1/8 turn.  

Steve

 

Just wondering how you go about tightening the tapered bearing?

[teoria_del_big_bang]

8 minutes ago, matt_baker said:

Do the tapered bearings have much impact on performance?

They do but unless they are damaged or not tightened correctly they are unlikely to have worn.

Was the mount new when you bought it ? If not then like me unless you ask and the mount has not had previous owners befor who you bought it from then you do not know what they did to it.

Steve 

[matt_baker]

1 minute ago, teoria_del_big_bang said:

They do but unless they are damaged or not tightened correctly they are unlikely to have worn.

Was the mount new when you bought it ? If not then like me unless you ask and the mount has not had previous owners befor who you bought it from then you do not know what they did to it.

Steve 

I bought it second hand from tomatobro two years ago, so I'll ask him what he did

[teoria_del_big_bang]

Always good to buy from a SGL member and I would think it will have been well looked after so might have had bearings replaced.

Regarding how much pre-load on the taper bearings then follow this procedure.

heq5-rebuild

You can imagine as you tighten the nut up that holds the bearing in place as you tighten it up you are squashing the two halves of the bearing together and as they are tapered, like wedges they start to wedge together.  All we are after is that there is no play in the direction you are winding the tightening nut (sorry for bad explanation not my best attribute). We do not want it any tighter than that as the more you tighten the more force needed to turn the two halves and unfortunately the stepper motors are quire easily stalled when doing fast moves so too much force required will cause them to stall.

Steve

Edited October 28, 2020 by teoria_del_big_bang

[matt_baker]

So is this essentially saying don't tighten up the counterweight collar too much and only nip it? 

 

[wxsatuser]

Taper rollers should spin freely with no play

[matt_baker]

Actually found something weird, I don't have the outer roller, just the bearing.

Edit: I do, just didn't look like it at first

Edited October 28, 2020 by matt_baker

[matt_baker]

Just had a look at the bearing and there seems to be a complete lack of grease inside too

Sorry for this too, I've got quite confused. Got a video here and was just wondering how far the bearing should go in or what you mean by pre-loading it?

Should've probably been wearing gloves too 

Apologies again, 

Matt

Edited October 28, 2020 by matt_baker

[matt_baker]

Just adjusted the float adjuster as it was too tight, now I'm out testing and my RMS value is 0.8"

 

Edited October 28, 2020 by matt_baker

[matt_baker]

Also here's the guiding graph