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Equipment Discussions >> Mounts

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greju
Carpal Tunnel
*****

Reged: 10/13/05

Re: Lx80 Multi-mount new [Re: DaveJ]
      #5498426 - 10/31/12 08:40 PM Attachment (72 downloads)

My bad. There are some similarities though.

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EFT
Vendor - Deep Space Products
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Reged: 05/07/07

Loc: Phoenix, AZ
Re: Lx80 Multi-mount new [Re: OzAndrewJ]
      #5499313 - 11/01/12 12:05 PM

It seems to me that the reason for the shallow pressure angle on the LX80 teeth is due to the very small diameter of the worm wheel. Higher pressure angle teeth would not be able to mesh properly. Looking at a worm from something like a CG-5 or LXD mount, they appear fairly similar. The difference is that the small GEM mounts use solid-mounted worm assemblies which then don't allow for slop other than simple backlash. Combining the same shallow pressure angle gears with a spring loading system will essentially never work without needing to apply far too much pressure with the spring assembly which causes its own problems and will never eliminate the slop problem with a heavier load.

I think that is what this comes down to. In presumably an attempt to eliminate backlash, they created a system that will not work with heavy loads. There is no way to put larger gears in that mount, so if possible, I would mod (or redesign) the worm assembly to be mounted solid. While you might have to leave some backlash, that would be better than uncontrollable slop. The problem is, with all the plastic in there, this might not be possible either.


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Mkofski
Pooh-Bah
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Reged: 07/19/11

Loc: Greenfield, Indiana, USA
Re: Lx80 Multi-mount new [Re: EFT]
      #5499382 - 11/01/12 12:49 PM

Ed,

Is the current state of the gearing somthing that a guy that offers hyper tuning service could address as an after market mod?


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EFT
Vendor - Deep Space Products
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Reged: 05/07/07

Loc: Phoenix, AZ
Re: Lx80 Multi-mount new [Re: Mkofski]
      #5499404 - 11/01/12 02:16 PM

Quote:

Ed,

Is the current state of the gearing somthing that a guy that offers hyper tuning service could address as an after market mod?




I don't really know. The ones that I was going to have a chance to tear apart got returned and without one right here to really get a good hand-on look at, I can't say. However, the pictures I have seen don't leave me very hopeful in regards to a different worm mounting option. In regards to changin the worm and wheel, it is hard to tell how much improvement could be made and cost (probably about $500 per axis) is difficult to justify.

It's difficult to get into this kind of thing with new mounts that are still under warranty and still have a lot of people questioning their purchase. Once you start tearing into them, and especially if you make physical modifications (i.e., not just tuning, lubing, etc.), then you are pretty much committed to keeping it, good or bad and $1000 is not pocket change for a lot of people who looked to the LX80.


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OzAndrewJ
scholastic sledgehammer
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Reged: 11/30/10

Re: Lx80 Multi-mount new [Re: EFT]
      #5499693 - 11/01/12 06:38 PM

Gday Ed

Quote:

It seems to me that the reason for the shallow pressure angle on the LX80 teeth is due to the very small diameter of the worm wheel.




So why does the ETX work???
That has a low pressure angle worm and a much smaller dia worm wheel.
( It doesnt track as well as a large dia wormwheel, but it does fit )

Ie the pressure angle could be achieved easily enough by selecting a worm "pitch" and diameter and then matching that to a proposed wormwheel dia and reverse engineering a suitable toothcount using industry standard tooth designs and sizes.
The Autostar code allows for different geartrain ratios in software, so the wormwheel toothcount could be anything that fits.

Quote:

I think that is what this comes down to. In presumably an attempt to eliminate backlash,




99.9% of backlash i have seen, ( where the worm is springloaded ), comes from the geartrains, not the worm to wormwheel interface. If they were trying to remove lash, the plastic geartrain would have been the first thing to re engineer.
( and that would also help reduce the PE being seen as well )

Andrew


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neilson
professor emeritus


Reged: 08/22/10

Re: Lx80 Multi-mount new [Re: OzAndrewJ]
      #5499927 - 11/01/12 09:01 PM

I think one of the reasons for the setup besides reducing backlash is to prevent damage to the plastic gears. When you have a larger OTA and you slew on high the spring and angle of the wormgear teeth allows it to disengage some. And when you stop slewing all that inertia is absorbed with the spring and the wormgear disengaging. Otherwise it might damage the plastic gears. This would mostly be true when slewing manually because it should slow down first if using the goto. Thats my thought anyways.

neilson

Edited by neilson (11/01/12 09:05 PM)


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OzAndrewJ
scholastic sledgehammer
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Reged: 11/30/10

Re: Lx80 Multi-mount new [Re: neilson]
      #5500028 - 11/01/12 10:01 PM

Gday Neilson

The pitch angle used on the worm pretty much means it is "non reversible". Ie any inertial loads coming from the OTA etc cannot ( normally ) flow back into the plastic gears.
The worm carrier would have to break before the plastic gears got any appreciable load transferred into them.
I reckon its just a result of a design choice based on cost,
that has been overhyped by the advertising dept.
( tho i must admit, i cant see how the two criteria ( advertising vs reality )
could be so far apart )

Andrew


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neilson
professor emeritus


Reged: 08/22/10

Re: Lx80 Multi-mount new [Re: OzAndrewJ]
      #5500120 - 11/01/12 10:55 PM

Hi Andrew,
Yes, I stand corrected. I think you told me this some time back but I had forgotten until now. I like your answer better anyways.

neilson


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EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: Lx80 Multi-mount new [Re: OzAndrewJ]
      #5500229 - 11/02/12 12:22 AM

Quote:

Gday Ed

Quote:

It seems to me that the reason for the shallow pressure angle on the LX80 teeth is due to the very small diameter of the worm wheel.




So why does the ETX work???
That has a low pressure angle worm and a much smaller dia worm wheel.
( It doesnt track as well as a large dia wormwheel, but it does fit )

Ie the pressure angle could be achieved easily enough by selecting a worm "pitch" and diameter and then matching that to a proposed wormwheel dia and reverse engineering a suitable toothcount using industry standard tooth designs and sizes.
The Autostar code allows for different geartrain ratios in software, so the wormwheel toothcount could be anything that fits.

Quote:

I think that is what this comes down to. In presumably an attempt to eliminate backlash,




99.9% of backlash i have seen, ( where the worm is springloaded ), comes from the geartrains, not the worm to wormwheel interface. If they were trying to remove lash, the plastic geartrain would have been the first thing to re engineer.
( and that would also help reduce the PE being seen as well )

Andrew




I've never been inside an ETX. Are the worms spring loaded? Certainly the loads are a lot less than what were anticipated with the LX80 which is why I would expect the ETX to work better even if the worms are spring loaded. I would say that the lower pressure angles work on the small GEM mounts because the worms are not spring loaded. I think that the problem with engineering becomes that, while you can make a better designed worm and wheel of small diameter, the teeth become smaller and smaller if you want to increase the pressure angle while maintaining reasonably high resolution and the machining becomes more difficult requiring greater precision and thus higher cost.

I think that we got out lines crossed on the second part. I think that they went with the spring loading to eliminate the worm/wheel backlash that is always present with a static worm system. The ideal spring loaded worm system would have no backlash from the worm and wheel leaving all of the backlash to result from the geartrain. The problem is that it may have been a bad choice in this case (I am actually finding spring loaded worms to be a pain in "better" mounts like the CGE Pro). The difference is that backlash in the worm/wheel can be compensated for by off-balancing to remove the gear slop whereas the backlash in the gear train becomes more complex and will usually require a firmware fix unless antibacklash gears are used (which take up too much space and are not in consumer telescope mounts to my knowledge).


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OzAndrewJ
scholastic sledgehammer
*****

Reged: 11/30/10

Re: Lx80 Multi-mount new [Re: EFT]
      #5500349 - 11/02/12 02:23 AM Attachment (52 downloads)

Gday Ed

Quote:

I've never been inside an ETX. Are the worms spring loaded?




Sort of. The worm is held in nylon bearings which sit in Orings then the worm carrier. The Orings act as a spring. Ref the piccy
The milky coloured washer has an internal sleeve which has an ORing around it.
This slides into the housing. Under load, the whole lot "floats" on the ORings.
The whole lot is "preloaded" by adjustment of the carrier.
Just for scale, the wormwheel is only 1.3inches in dia and has 60 teeth,
so a proper wormwheel for the LX80 size should be no problems.

Quote:

I think that we got out lines crossed on the second part. I think that they went with the spring loading to eliminate the worm/wheel backlash that is always present with a static worm system.




Understood, but up till now, ALL Meade worms ( that i have seen ) use a proper tooth profile and a very light spring load to ensure they stay in contact, not the massive spring used on the LX80.

Quote:

The difference is that backlash in the worm/wheel can be compensated for by off-balancing




But that too has its tradeoffs.
ie with a fixed wormcarrier, any eccentricity in the wormwheel creates differences in the tooth contact points, and as they change this can affect PEC.
Also, most GEMS dont really care about the lash as they only ever go one way during normal operation, and guiding is a simple slow down or speed up exercise . The LX80 also has to do double duty as an altaz mount, and for it to work correctly, the backlash has to be "consistent", even if it is large.

Andrew


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Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Lx80 Multi-mount new [Re: OzAndrewJ]
      #5500659 - 11/02/12 10:20 AM

Elastomers aren't true springs, and change properties with temperature. A lot of the "ETX works" would appear to be not asking much from it.

-Rich


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OzAndrewJ
scholastic sledgehammer
*****

Reged: 11/30/10

Re: Lx80 Multi-mount new [Re: Starhawk]
      #5501171 - 11/02/12 04:05 PM

Gday Rich

Quote:

Elastomers aren't true springs, and change properties with temperature. A lot of the "ETX works" would appear to be not asking much from it




Fully agree, but i was just answering Eds comment re how the ETX worm was preloaded. In reality, the ORing method is not very "responsive", but it does "ooze during operation" thus keeps the gears in contact.


The main point of the piccy was to show a low pressure angle worm could be made in the sizes we were discussing.

Andrew


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Starhawk
Space Ranger
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Reged: 09/16/08

Loc: Tucson, Arizona
Re: Lx80 Multi-mount new [Re: OzAndrewJ]
      #5501879 - 11/03/12 01:03 AM

Gday Andrew,

I'm with you there. Going from the way the details are designed, I can't imagine the same engineering authority was behind all of these designs. What does that mean? I'm really not sure. The LX80 has been profoundly difficult to account for.

-Rich


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dksolar3294
member


Reged: 08/22/12

Re: Lx80 Multi-mount new [Re: Jack Huerkamp]
      #5524956 - 11/17/12 07:32 PM

Jack, Now that your machinist has made a LX80 tripod top plate replacement, is he interested or willing to make more? at what $cost for a single?

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Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Lx80 Multi-mount new [Re: dksolar3294]
      #5527094 - 11/18/12 11:50 PM

I think Jack is working on determining the efficacy of his new plate, and using the mount in any case- see the other LX80 thread active at the moment.

-Rich


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Jack Huerkamp
Vendor - Waning Moon


Reged: 10/13/05

Loc: Louisiana
Re: Lx80 Multi-mount [Re: dksolar3294]
      #5527648 - 11/19/12 10:34 AM

The machinist is ready to make more of them for me. And the final price depends on how many I get and the shipping from Canada.

Regarding the mount, I tested it at DSRSG a few weeks ago. Rod Mollise was there and has commented on what he saw on his new blog. Its contained in his report of the DSRSG. His blog can be found at:

http://uncle-rods.blogspot.com/

If anyone is interested in getting a tripod top replacement, contact me directly.

Jack Huerkamp


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Axle
member
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Reged: 04/19/12

Loc: Lake Powell
Re: Lx80 Multi-mount new [Re: James Cunningham]
      #5562641 - 12/09/12 03:25 PM

Well, I bought a LX80 by accident because I ordered it last April, kind of forgot about the order and then received it about a month or so ago. I've used it a few times now and actually have enjoyed it.

I've read all the LX80 threads and was concerned about the lightweight tripod top. Also, upon first inspection and use, I sort of thought that this particular LX80 might not have much of the AZ slop being discussed.

Thus, in order to avoid a tripod failure and to try and gain some tripod stability and minimize vibration, I asked a machinist friend to make a beefier top.

Here's our version the LX80 tripod top:



The top is billet aluminum and the leg lugs are steel. The dull finish is from bead blasting.



The new top width is the same width as the attachement bolt posts on the OEM top. The allen bolts are about 2 1/2 inches long.



The little hole by my thumb is for the OEM bubble level; LOL...



The new top basically has the same dimensions as the original top.



Although the center rod attachment lowers the tripod spreader triangle a little, it still fits fine.



Everything assembles perfectly using the homemade top.



Inlcuding counterweights, the above is about 50 pounds or so.

My only use is visual and outreach. Although I've used the LX80 several times in alt/az, I have not set it up in EQ yet. Last night was the first use with the new top.

The new top definitely removes any worries that a leg might break away. But maybe there was only slight gain in overall vibration removal, if any.

To be honest, last night was the first time I really checked the LX80 az slop being discussed in the other thread. I now better understand the issue but am not really worried about it since I am visual only.

Anyway, I wanted to share my solution to the LX80 tripod top weakness. Before I asked my friend about machining a new top, I was going to install small diameter tie bolts on the OEM top for increasd strength and fill the whole underside area with epoxy resin.

So far, I like the LX80 because it is relatively easy to set up and I like Sandy Wood LOL... Next I will try the EQ configuration to see how stable that is.

thanks,
Axle


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Mkofski
Pooh-Bah
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Reged: 07/19/11

Loc: Greenfield, Indiana, USA
Re: Lx80 Multi-mount new [Re: Axle]
      #5562650 - 12/09/12 03:32 PM

Axle,

Thanks for the information. That top is nice looking. Is your friend interested in making any more? If so, let us know the price.


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Jack Huerkamp
Vendor - Waning Moon


Reged: 10/13/05

Loc: Louisiana
Re: Lx80 Multi-mount new [Re: Axle]
      #5563167 - 12/09/12 09:27 PM

Axel,

I noticed that when I added the replacement tripod top that my machinist developed, the mount was more steady than with the stock top. But some of that may have come from not having to fear overtightening the spreader and having a leg snap off. If you are going to use the LX80 for purely visual observing, you may find it satisfactory in Alt-Az mode. The damping time for mine when using a C9.25 was about 5 seconds if I tapped the diagonal. I don't know how heavy your refractor is, but it's longer than my SCT, so it may result in slightly higher vibration. My damping time doubled when I set the scope up in EQ mode.

Yours truly,

Jack Huerkamp


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DuiA1
super member


Reged: 05/07/12

Loc: Ontario, Canada
Re: Lx80 Multi-mount new [Re: Jack Huerkamp]
      #5563225 - 12/09/12 10:00 PM

The new top looks very substantial. Nice. What js your damping time in az and equatorial mode? What's the thickness of the material behind the Allen bolt on the U section?

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