Pulsar Dome assembly

[markse68]

5 hours ago, markse68 said:

That's what I'd do- least effort and risk of damage to other bits. Buy A4 SS replacements and nuts so you don't have the same problem next time. Guessing they are coach bolts with square shanks- well the one that spun no longer has a square hole to fit into so best get slotted or allen socket heads

Thinking about it I’m not sure that’s going to work with the square shank- you might not be able to pull the bolt through if the square won’t clear the hole 🤔 Here’s a bit of a left field thought- the rust is jamming the nut so if you could remove the rust the nut would come off easily. Vinegar dissolves rust quite quickly but you need to immerse it in the vinegar. You could try wetting them with vinegar so it soaks into the nut threads then daubing the exposed thread in tomato ketchup and maybe wrapping in cling film to prevent it drying out- leave for a day or more then try again? Might help 🤷‍♂️

[MCinAZ]

7 hours ago, markse68 said:

That's what I'd do- least effort and risk of damage to other bits. Buy A4 SS replacements and nuts so you don't have the same problem next time. Guessing they are coach bolts with square shanks- well the one that spun no longer has a square hole to fit into so best get slotted or allen socket heads

I'll second the suggestion for stainless hardware, but be sure to apply anti-sieve to the threads before assembly or you'll likely be back in the same boat the next time you need to remove the fasteners. If it were me, I would go with button head socket cap screws.

[brit 50]

On 09/05/2020 at 16:10, JeremyS said:

So the wheels arrived today 🙂

They are a bit narrower tread than the existing ones, although the diameter is correct. I think they will ok.

So the first job was to remove the bolts holder on the existing wheels. I had already primed with Plus Gas and added some more for good measure. Some of the bolts are corroded, so I started with a non-corroded one. Using a spanner, I released the nut and got it moving. But then it stopped. The problem is that the whole bolt rotates freely. Ideally I would have liked to use a screwdriver in the bolt head to stop this rotation while working the nut with the spanner. But the bolts have a smooth domed head - no slot!!!

I could try and grip the bolt with pliers, but what would likely damage the bolt thread and I'd never get the nut off.

Any suggestions?

I know its late but i swapped out all of my early pulsar wheels for new ones, then had to replace those because of flat spotting, went for these in the end. cheap as chips and no problems.

 

https://www.bilcastors.co.uk/product/bzv050wny1/

[JeremyS]

1 hour ago, brit 50 said:

I know its late but i swapped out all of my early pulsar wheels for new ones, then had to replace those because of flat spotting, went for these in the end. cheap as chips and no problems.

 

https://www.bilcastors.co.uk/product/bzv050wny1/

Thanks. Did you use the same mounting hardware for the new wheels?

[sloz1664]

I was lucky all my wheels & bearings were ok after a good clean & new bearing grease. But, all the nuts, bolts and washers were replaced by stainless steel equivalents.

Steve

 

[michael8554]

18 hours ago, brit 50 said:

I could try and grip the bolt with pliers, but what would likely damage the bolt thread and I'd never get the nut off.

Any suggestions?

Lock two more nuts together on the end of the thread.

Hold the one nearest the wheel with a spanner while you loosen the rusty one with another spanner.

Then use Molegrips on the bolt head once you have the rusty nut loose enough.

Michael

[michael8554]

19 minutes ago, michael8554 said:

Hold the one nearest the wheel with a spanner while you loosen the rusty one with another spanner.

Or the one furthest away, I can never remember which  - whichever one doesn't start loosening when you attack the rusty one :->

Michael

[JeremyS]

5 minutes ago, michael8554 said:

Or the one furthest away, I can never remember which  - whichever one doesn't start loosening when you attack the rusty one :->

Michael

Thanks Michael. I still haven't started this job as I'm not sure I really have the proper skills. I needed to look up "mole grips". I might have to get a proper man in (as my wife calls them) to do the job. Trouble is not sure where I'd find one 🙂

 

[michael8554]

A pair of pliers should suffice.

Michael

[Nigella Bryant]

I just cleaned and applied new grease to my rollers after a relocation of my dome. Seemed to come up well even though two were jammed at one point but some penetration oil did the trick.

[brit 50]

On 24/06/2020 at 17:16, JeremyS said:

Thanks. Did you use the same mounting hardware for the new wheels?

Hi, sorry for delay, i just replaced the 8mm stainless bolts and nylock nuts with washers all from toolstation, bolts are 8mm x 60mm and have a shoulder  (no thread part) that the nylon wheels run on.

[brit 50]

Just a little tip when using stainless steel nuts and bolts etc, use a drop of grease on the threads because the thread will gall up without it and prevent from tightening or loosening

[Nigella Bryant]

3 hours ago, brit 50 said:

Hi, sorry for delay, i just replaced the 8mm stainless bolts and nylock nuts with washers all from toolstation, bolts are 8mm x 60mm and have a shoulder  (no thread part) that the nylon wheels run on.

I just used the same hardware as before with plenty of grease when I refitted the wheels. Dome rotates a treat, better than before. Did the shutter rollers and added a roller each side of the middle of the dome shutter too. Made it slick to open now, again much better than before as I was struggling to close it. All manual, not motorised.

[JeremyS]

As I mentioned above, the wheels have been in need of replacement on my Pulsar Observatory, Mark 1, installed on 1st June 2004. 

I've had the replacement wheels in stock for some weeks, but was worried about whether I had the right competence to do the job. I decided that what I needed was a:

doing.

I was put to shame by the stunning job that @Nigella Bryant has done, so I asked a really helpful engineering contact to do it for me:

James has never done a job like this, but he was brilliant. He even managed to replace all the wheels without the need to take the dome off the walls. And he replaced the original aluminium nuts and bolts with stainless steel. Much better:

And here's the box of discarded wheels. The first delaminated last summer, but loads more have started to delaminate this spring and summer:

It took James all day to complete the job, so saving me a lot of time. I've learnt a few things in the process, but mainly what "mole grips" are - a term that was new to me. I must say that the toolkit in James's van would have made even @johninderby's and @andrew s's eyes stand out on stalks. Now I'm looking forward to the new season with a smoothly rotating observatory.

 

 

[andrew s]

Good to know your limitations @JeremyS. I have been spending my time building a cat pen (6ft x 6ft X 12ft) as we are having to foster my daughters two Burmese cats for 3mth as the are moving from London to Manchester. Our lady Burmerse only just allows her brother in to feed so it's isolation for the boys.

I had planned to buy one but it was 8 weeks delivery . How I wish our garden was not on a hill!

Regards Andrew 

PS intended to say proper job on your dome.

Edited August 17, 2020 by andrew s

[Nigella Bryant]

Brilliant Jeremy, you'll not regret it. Smooth operation from now on. Roll on some clear skies. I've been waiting for clear skies this last ten days to polar align the mount in my obsy. According to the forecast August is out 😭😭😭

[michael8554]

Hi Jeremy

Interested by your images of the new wheels.

Did yours have double wheels originally ?

If not, why did you go for double ?

One of the wheels on my Mk 1 falls off the track at a certain point, double or much wider wheels would stop that on mine.

Michael

[JeremyS]

1 minute ago, michael8554 said:

Hi Jeremy

Interested by your images of the new wheels.

Did yours have double wheels originally ?

If not, why did you go for double ?

One of the wheels on my Mk 1 falls off the track at a certain point, double or much wider wheels would stop that on mine.

Michael

Hello Michael,

I couldn't find any 50 mm wheels with the same diameter as the originals - Pulsar couldn't help either (they use different wheels on the newer domes). So I took the advice in the thread above and ordered some narrower ones. The guy doing the job suggested to double them up.

[JeremyS]

20 minutes ago, andrew s said:

Good to know your limitations @JeremyS.

A long list, Andrew. But well known 🙂

 

[michael8554]

27 minutes ago, JeremyS said:

So I took the advice in the thread above and ordered some narrower ones.

Those 18mm ones are the same width as my single ones !

Looks as though a previous owner has not fitted the right replacements !

Does your door foul on the lower shutter rail brackets when the shutter is opposite the door ?

Michael

[JeremyS]

1 minute ago, michael8554 said:

Those 18mm ones are the same width as my single ones !

Indeed, something not right there, Michael. I would have probably gone ahead and installed single wheels, but it was my "proper man" who pointed out the problem.

2 minutes ago, michael8554 said:

Does your door foul on the lower shutter rail brackets when the shutter is opposite the door ?

Yes, but not a problem as I close the door when I'm inside.

[michael8554]

42 minutes ago, JeremyS said:

Yes, but not a problem as I close the door when I'm inside.

So you stop guiding and revolve the dome when nature calls ?

Michael

[JeremyS]

10 minutes ago, michael8554 said:

So you stop guiding and revolve the dome when nature calls ?

Michael

Strong bladder, Michael 🙂

 

[michael8554]

8 minutes ago, JeremyS said:

Strong bladder, Michael 🙂

Not my strong suit

Michael

[JeremyS]

First night with the new dome wheels, last night. Was like having a new dome. Wish I’d got on top of this job earlier!