I wanted to ask your advice please. I've recently acquired a second hand MI-250 (actually there aren't any new so the second hand bit is a little superfluous). Anyway, I put it together and started testing it and am a bit worried about the DEC worm drive - it grinds and bumps.
I'm advised by someone that these things are part of the learning curve, are normal and don't become an issue when there's a proper load on the mount (i.e a scope and counterweights).
I wanted to ask the learned community here - it that right? Are these kinds of things normal for large direct drive style mounts?
I've got some new bearings coming to me because I separated the worm drive from the worm block to determine what was causing the grinding noise and odd DEC drive behaviour and you can see the state of the old bearings here (or here) and hear them operating here - but my original question stands - is this normal?
I doubt that grinding noises are standard fare for a mount that was of the quality that this was when new. Never had the pleasure of using one but it was my dream mount...
Was this disclosed to you prior to purchase? Was this the one sold on the trader?
I think you need to take it up with the seller, but having pulled it apart yourself, you may have relinquished any recourse there. Looks like it may be simple enough to rebuild regardless, but you shouldn't have had to.
I agree with Lewis here , it should be quite simple to clean , re-grease and adjust , these are high quality and built to tight tolerances so it should run perfectly if nothing has been damaged .
Good luck .
No is the answer to the first question, second is yes - but, I am confident I can get it running to spec. My new bearings arrived today and they are smooth, fit perfectly and I'll do a re-grease of the DEC drive while I'm at it.
Instructions on the web for this are spot on and have helped. Fingers crossed!
After doing some repair work and some adjustments (more needed) it has come better but not near what was advertised.
Advice for those not seasoned and overly trustworthy: Insist on a video of the thing working before you purchase it if you are in any way unsure about the sale. This was an expensive buy for me and I was hoping that the advertised specification were correct as the MI-250 mount is praised all over.
My fortune hasn't been great lately so I've had to spend a significant amount of time 'repairing' it before it comes good. No doubt I'll need to spend more time 'adjusting' to get it close to operating specification because it's not there yet.
Disappointed to hear the same story over and over again in this forum. I suppose it could be forgiven if the mount was sold at a significant discount, but if my experience is anything to go by, the price was also a premium one.
Hopefully you will get it operating as well as these mounts are reputed to work.
Regards
Andrew Lockwood.
Take it up with Astronomy Alive. I remember the multiple times it was listed - no mention of defects or issues just the usual superlatives.
I just fear now you have disassembled and replaced parts you have no legal recourse.
Good luck Simon.
I recall the listing as well as I had a brief amount of interest in an additional mount before changing plans....I recall it was advertised as being in Excellent Condition.
Quote:
Originally Posted by alocky
Disappointed to hear the same story over and over again in this forum. I suppose it could be forgiven if the mount was sold at a significant discount, but if my experience is anything to go by, the price was also a premium one.
Hopefully you will get it operating as well as these mounts are reputed to work.
Regards
Andrew Lockwood.
I have purchased quite a few items on ice trades without a hitch so largely most sellers are genuine and reliable.
Unfortunately there are the rare individuals that mislead and cannot be trusted to tell the complete picture
Whether the goods bought were from an individual or even a retailer, (check your receipt), you can pursue a refund or return via VCAT (Victorian Civil and Administrative Tribunal)
I would think that the gears / meshing and bearings issue you have experienced would definitely call into question whether the item was of "merchantable quality"
VIC GOODS ACT
GOODS ACT 1958 - SECT 19
Implied conditions as to quality or fitness
Subject to the provisions of this Part and of any Act in that behalf there is no implied warranty or condition as to the quality or fitness for any particular purpose of goods supplied under a contract of sale, except as follows—
S. 19(a) amended by No. 6716 s. 2(Sch. 1).
(a) where the buyer expressly or by implication makes known to the seller the particular purpose for which the goods are required so as to show that the buyer relies on the seller's skill or judgment and the goods are of a description which it is in the course of the seller's business to supply (whether he be the manufacturer or not) there is an implied condition that the goods shall be reasonably fit for such purpose: Provided that in the case of a contract for the sale of a specified article under its patent or other trade name there is no implied condition as to its fitness for any particular purpose;
(b) where goods are bought by description from a seller who deals in goods of that description (whether he be the manufacturer or not) there is an implied condition that the goods shall be of merchantable quality: Provided that if the buyer has examined the goods there shall be no implied condition as regards defects which such examination ought to have revealed;
(c) an implied warranty or condition as to quality or fitness for a particular purpose may be annexed by the usage of trade;
(d) an express warranty or condition does not negative a warranty or condition implied by this Part unless inconsistent therewith.
The latest seller should be well aware of its operational ability based on the fact he claims it was in his observatory replaced by an ASA DDM85 mount .
I would hard save copies of all the sales adverts on it before they are deleted - screen shots at least
Thanks for keeping up with this guys. Yes, that's the unit I purchased.
I'm testing my new bearings and repairs when I next get some clear skies in the hopes that I have repaired it. How on earth it got a PE of +-3 with those bearings and the vibrating worm is beyond me.
IF I've managed to do a good job then the mount will be a keeper (and maybe I can offer a repair service!). Otherwise I will be looking at my options.
To my mind I'm going above what may reasonably be expected in order to make the sale work - in good faith, so that if even after I've attempted repairs its still not of merchantable quality then I will take it further.
I know that's a risk because it could be said that I have made matters worse by attempting a repair. I don't think that has happened yet however, visual and audio tests indicate it's better than it was before. Fingers crossed for a few clear nights to test it.
It took me 4 years and almost as much as I paid to rectify what was advertised as 'the finest example' of a 4" unitron. I was fortunate enough to be able to find or have remanufactured a lot of parts after scouring the world for three years. It's always going to be a risk buying used and obsolete gear. However we now fortunate to have a forum where the facts can be presented objectively, to prevent others from falling into the same trap.
Hope it works out, you've got yourself a beautiful bit of gear, despite the abuse it's suffered.
Cheers
Andrew
Quote:
Originally Posted by baileys2611
Thanks for keeping up with this guys. Yes, that's the unit I purchased.
I'm testing my new bearings and repairs when I next get some clear skies in the hopes that I have repaired it. How on earth it got a PE of +-3 with those bearings and the vibrating worm is beyond me.
IF I've managed to do a good job then the mount will be a keeper (and maybe I can offer a repair service!). Otherwise I will be looking at my options.
To my mind I'm going above what may reasonably be expected in order to make the sale work - in good faith, so that if even after I've attempted repairs its still not of merchantable quality then I will take it further.
I know that's a risk because it could be said that I have made matters worse by attempting a repair. I don't think that has happened yet however, visual and audio tests indicate it's better than it was before. Fingers crossed for a few clear nights to test it.
1. The buyer asked me as seller to assist with the motors, when they didn't work. I told him what to do and they then worked. Astronomy 101 stuff. why was this even asked ?
2. He then asked questions about gearing, and again I assisted with guidance. Then I heard nothing further. I repeat then heard nothing further ?
Then I get a couple of calls from people I know on IIS asking whether this guy knows enough to run this unit. I cannot answer this, ask him.
This thread is the usual tangents going off all over the place without being intimately involved. With one side of the story and totally inadequate actual detail.
Great stuff guys - shooting first without asking any questions
Seriously guys, this stuff is premier gear and needs care, and attention to detail, to get operational. I get a little of this from time to time when people buy gear and due to the learning curve of this level of gear have issues.
Sad, but don't bag people when you aren't involved. Poor behaviour from some of you. Particularly a PM received today from someone that knows who he is, and doesn't know me whatsoever, his language was appalling, get a set of manners mate
To the others that rang me to support, thanks guys, appreciate your caring
There's always two sides to a story, but usually they overlap somewhere in the middle. The ads quoted here all claim it to be in excellent condition. Since it's a photographic mount, it should be easy enough to demonstrate the level of performance it is capable of delivering by showing some of the incredibly sharp and well guided images it must have acquired while serving in the observatory?
Most gear of this quality is usually advertised with PEC graphs, autoguider outputs, or at least an example of an image. +-3" is pretty damn good performance, and as Carl Sagan said - 'extraordinary claims require extraordinary evidence'. If it was only ever used visually, then it is disingenuous to describe it's performance, because these problems will not show up visually.
Having said that - these things are exposed to the elements when they're working, so it's unrealistic not to expect it might need a bit of work. Even ultra premium mounts like the DDM85 require new bearings eventually! Pity mine needed them sooner rather than later...
Anyway credit to Simon for sticking with it, staying within the facts, not getting personal and not enumerating his mates who will come looking after school is out...
Seriously guys, this stuff is premier gear and needs care, and attention to detail, to get operational.
I always thought premier gear just required electricity of the right voltage and it would run ( without making odd noises )??????
Sure getting it aligned etc may require a bit of tweaking,but just getting the motors to run smoothly doesnt require a degree in mount maintenance.
Mountain Instruments MI-250 questions
I agree with Lewis here , it should be quite simple to clean , re-grease and adjust , these are high quality and built to tight tolerances so it should run perfectly if nothing has been damaged .
