Hotech Laser

[alan potts]

I bought this secondhand about 3 years ago I guess and I have to say I have been very happy with it and what a good tool it is. I have very rarely screwed the clamping device up which is part of the 2 inch focuser fitting, I find it perfectly good enough and tight fitting just pushing it into the focuser.

What has happened is the rubber gromits or bands around the 2 inch sleeve seem to have got large, all of a sudden as it happens, and now it snags on the compression ring in the focuser. Anyone know if it is possible to get spares for this, though I am sure I could continue to use it with only the 1.25 fitting and a reducer?

[DRT]

I bought one of these second hand a few weeks ago and have noticed the same thing with some focusers. I wonder if there is a way of shrinking the rubber rings back down to siz through temperature changes - e.g. warm them up in hot water and then put them in the freezer to make them contract. If replacements can be found I might try it.

[Pete Presland]

Might be worth contacting http://www.hotechusa.com/category-s/22.htm direct they might be able to help, it would be shame not too get full use out of such a great device.

[alan potts]

Thanks for the link but getting anything from the states is a nightmare here.

Derek, It was keeping the laser outside that seems to have caused it, it was very very cold a few weeks back, but I will try a warm bath for them, nothing to harm.

[DRT]

Ah, I've been keeping mine in the shed, which probably explains it.

 

I read the blurb about this device this morning after reading this thread and it occurred to me that there is a fundamental flaw in the logic.

These rubber rings are designed to ensure the laser sits absolutely central within the focus tube and is not skewed by the use of a knurled screw or compression ring. From the point of view of aligning the mirrors this feels like a good thing, but the reality is that your eyepieces will not be held in the focuser by the same method as the laser, so the eyepiece will not be exactly in alignment.

Would it not be better to secure both the laser and the eyepiece in the focuser using the same method?

[alan potts]

I think to be honest we are both using very good equipment which hopefully is engineered to a high standard, I can't really seeing it making a lot of difference, I mean how much slog is there in a TV eyepiece and a similar diagonal or Moonlite /Feather focuser . The odd thing is I have never really tighened these things up to remove movement which wasn't really there, I maybe did it the first and second times I had it and that it.

I will get the bath water ready.

[alan potts]

Derek

Amazing I put them in the washing up water and they are now 10 sizes smaller, so keep it indoors and I imagine all will be well. Great tip that of yours, many thanks. Of course keeping it outside in summer I have never noticed a problem and I only moved it out in May, so that's the answer.

alan

[DRT]

Very true, Alan. I use a TV extension tube in a MoonLite focuser on my Dob and even if I chose not to tighten anything there would be very little movement. I'll bring my Hotech in from the shed when the rain stops

Glad to hear it is sorted

[Dave In Vermont]

Looking at the Hotech website to get an understanding of what is going on with these, I think I see a way around the rubber-ring troubles.....

You could dispense with the Hotech 2" - 1.25" adapter altogether and use a different one - such as a Baader click-stop one. Or an Antares twist-lock (less £'s). These don't seem to be adversly affected by the cold.

Dave

[DRT]

That is what I have been doing, Dave, when the Hotech 2" adapter won't fit. Hopefully the solution we found here will remove the problem and it's no issue for me to keep the device in the house.

[Tinker1947]

Ok i skipped a few reply's so this may have been mention, the rubber isn't expanded due to the normal twisting action to make it grip in the tube not being unscrewed far enough, i have one and it seems ok, been in its box in the Obby for maybe a year and worked fine last time i used it......one other thing i didn't buy the 2" adapter as i have a Baader 1.25 - 2" Click-lock Adapter which grips the Hotech and sits in the tube nicely......

 

This type of Rubber band might work...

http://www.grommets.co.uk/products/cord-rings/

[alan potts]

Tinker,

It is nothing more than the cold, it gets much colder here than anywhere in England, we had minus 28.5 the other week and it was after this I noticed the problem. Now it's inside in plus 24 degrees and it is as good as new.

[Tinker1947]

Just now, alan potts said:

Tinker,

It is nothing more than the cold, it gets much colder here than anywhere in England, we had minus 28.5 the other week and it was after this I noticed the problem. Now it's inside in plus 24 degrees and it is as good as new.

So best to keep them inside in the warm then, glad its sorted out ok..

[Lorne]

On 06/02/2016 at 08:44, DRT said:

Ah, I've been keeping mine in the shed, which probably explains it.

 

I read the blurb about this device this morning after reading this thread and it occurred to me that there is a fundamental flaw in the logic.

These rubber rings are designed to ensure the laser sits absolutely central within the focus tube and is not skewed by the use of a knurled screw or compression ring. From the point of view of aligning the mirrors this feels like a good thing, but the reality is that your eyepieces will not be held in the focuser by the same method as the laser, so the eyepiece will not be exactly in alignment.

Would it not be better to secure both the laser and the eyepiece in the focuser using the same method?

I agree with this, try both methods to secure the Hotech, I did and could see movement of the laser on the primary mirror around the centre donut - even on my  old scope with the Moonlite focuser. I now always use the thumbscrews to secure both the collimator AND eyepieces. 

[jetstream]

My Catseye sight tube and Cheshire work in the cold

Big dob primary collimation would sure be easy with a Glatter Laser and TuBlug though.....

[alan potts]

18 hours ago, jetstream said:

My Catseye sight tube and Cheshire work in the cold

Big dob primary collimation would sure be easy with a Glatter Laser and TuBlug though.....

It;s so cold where you are sometimes I am surprised you don't stick to the metal. The last two nights the Hotech has been fine kept in the warm, it must be like my wife.

[jetstream]

4 hours ago, alan potts said:

It;s so cold where you are sometimes I am surprised you don't stick to the metal. The last two nights the Hotech has been fine kept in the warm, it must be like my wife.

It's -32c here right now Alan big cold front. Great transparency last night for a while- had a chance for the Cone, but by the time I found the spot on the spot, the trans went. I have insulated mechanics gloves that are working the best yet, east yo use the collimation tools with them.

[alan potts]

Wow Gerry that's cold, I was out the other week here when it was minus 20 odd in the morning and I was slowly losing the will to live, but clear as a bell.

 

Alan