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Ed Byers Worm and Gear: New Owner, Advice Needed

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#1 Toups

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Posted 13 December 2020 - 03:15 PM

I broke down and bought myself yet another project.  I am the proud new owner of a lovely piece of art, a 7.5" Ed Byers gear with slip clutch, worm, and drive motor. The drive motor is a Hurst 1/2 rpm Model A timing motor with a capacitor and wiring diagram.

 

Byers_Gear.jpg

 

So now I need to design a mount around it.  A few practical questions:

 

1) Is there any sort of "users" manual available on the web?

2) How to best align and mesh the worm with the gear.  What to do and more importantly, what not to do.

3) I assume it s it safe to just move the telescope via the slip clutch with the worm gear engaged.

4) Lubricate or dry?  If not dry, would HELIMAX-XP Camera Telescope Optical Instrument Focusing Helicoid Grease w/ PTFE be a good candidate?

5) Other hints or suggestions.

 

The mount will need to be portable.  For ease of construction, the mount body will probably be made of wood.  Bearing design and layout is TBD but at least I have an exquisite RA drive gear to design around.  The trick will be building a portable system worthy of this gear set.


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#2 Couder

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Posted 13 December 2020 - 03:29 PM

This is what Ed Byers wrote me in an email:

 

Jon:

If the gear is completely enclosed in a dust-proof housing, then you should a grease that will not freeze (if you live in a cold climate), to the gear teeth and worm threads.

Ed Byers

 

you want to make a mount instead of buying one and putting the gear on it?


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#3 Toups

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Posted 13 December 2020 - 04:45 PM

Thanks for the comment from Ed Byers.

 

<SNIP>

 

you want to make a mount instead of buying one and putting the gear on it?

I enjoy building things but probably have too many projects in the works.  Also DIY, besides sometimes saving money (but not always LOL) for similar performance it also allows one to gradually invest in the hobby rather than doing things in (fewer) larger purchases.

 

I know I'm a glutton for punishment.
 



#4 don clement

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Posted 13 December 2020 - 04:54 PM

I am building a small GEM and like you have an almost identical Byers 8" worm and worm gear set.  Byers told me personally about protecting the  greased worm set from dust as that will destroy the precision he machined into it.  I am going to mount this gear set in a dust proof enclosure on the back end of the RA axis. I am also going to spring mount the worm similar to Porter from the original ATM books as shown.

 

Don

 

IMG_6400Web.jpg

 

 

porterwormweb_zpsc944e035.jpg


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#5 duck

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Posted 14 December 2020 - 12:58 PM

regarding mesh and alignment of the worm and wheel...if you don't have accurately machined surfaces which guarantee alignment, alignment can be easily felt my holding the worm against the wheel.  Even with machined surfaces, the worm must be located correctly on the plane of the wheel.  Generally done by feel.  I use lithium grease on the mesh.  Make sure to allow for a touch of backlash.  Regarding spring engagement, I found it not to work.  There is a 19 deg pressure angle on the tooth engagement.  Any torque disturbance acts through the pressure angle and moves the spring loaded worm a bit, increasing tracking error.  Byer's disagreed with me on that.  It may have been because there is a bunch of torque disturbance in my homemade mount compared to Byer's precision mounts.


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#6 duck

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Posted 14 December 2020 - 01:07 PM

Since you are new to this piece of art, I will offer some more advice.  See the two dowel pins poking into the clutch plate?  Keep those oiled.  For the clutch to work properly, the clutch plate must slide freely on the dowel pins.  Serving the clutch involves taking the clutch plate off the hub and cleaning the Delrin ring wih a rag (no solvents!) and cleaning the mating anodized surfaces with acetone. 


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#7 Chucke

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Posted 14 December 2020 - 02:21 PM

You can get a general feel for alignment by manually turning the worm when it is engaged.  It should feel the same both directions.  If it does not you are out of alignment.  When you are close but not perfect you may not feel a difference.  I align my gears with a depth mic, gauge blocks, and shims.  It is much more difficult with the single ended worms like yours because the measurement points are really close together.  With the double ended worms like Don's the measurements are several inches apart and it is not too difficult to get it within 0.0005" or so over 6".  As mentioned in the above posts, worm gears require some backlash to work properly.  I usually leave about 0.002".  After that I adjust the spring load.  Adjusting the spring load is tricky.  Too tight and the gear binds up, too loose and it backs off when under load causing even worse backlash.

 

FYI, the thin cheap aluminum foil is usually about 0.0005" thick.  Byers achieved his alignment via precision machining and years of experience.


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#8 don clement

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Posted 15 December 2020 - 01:33 PM

IMO it is important to use a compliant mechanism as the hinge or pivot when spring loading the worm against the worm gear. This is because the movement is going to be very very small and pivot stiction could cause the worm not to linearly follow the  movement (stick slip) caused by runnout of both the worm and worm gear bearings  and/or machining inaccuracies.  Byers minimized that BTW. My plan is not to pivot but to use a parallel leaf-spring flexure made with BeCu sheets attached to the bottom of the worm block. 

 

Don

 

2-Leaf-springs-in-parallel4.png


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#9 Messyone

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Posted 15 December 2020 - 06:48 PM

This might help.

 

 

Attached Thumbnails

  • Byers Gear instructions #1.jpg
  • Byers gear instructions #2.jpg

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#10 Messyone

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Posted 15 December 2020 - 06:54 PM

How I bolted my 7.5" Dec gear to my 2" pillow block mount. The RA has a 10" Byers gear both out in the open and both work beautifully though I do have to wipe them down and lube often. I read somewhere that Silicone spay works (it does) but I prefer Lithium Grease that is used by Bicycle mechanics.

 

Attached Thumbnails

  • Byers gear mounting.jpg

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#11 Toups

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Posted 15 December 2020 - 07:08 PM

This might help.

Yes it does!  Thanks very much.  It's exactly the type of information I was hoping to find. 

 

Thanks to all who have replied so far.  Lots of good information and tips so far.

 

Thanks, again!


Edited by Toups, 15 December 2020 - 07:15 PM.


#12 Toups

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Posted 18 December 2020 - 07:32 AM

Is there information sheet on the clutch mechanism?

 

Thanks!



#13 Toups

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Posted 18 December 2020 - 02:04 PM

Well, was working up the design of a mount using pillow block flange bearings and pulled out the gear and worm to make a few measurements. 

 

Something didn't seem right and well I didn't get what I thought I had ordered.  ohmy.png

 

The ad on the bay said it was a 7.5 inch gear.  While measuring a few things, I realized this looks bigger than 7.5" so measured the diameter and it's a 9 inch gear. snoopy2.gif

 

Gear and Ruler.jpg

 

This wasn't a case of the seller shipping the wrong item; this was the only Byers gear that the particular business has had listed now or over the past few years.  My guess is they went to the web and found the closest picture which happened to be a 7.5 inch gear and made the ad accordingly.  Unfortunately, I wonder if the seller is a business that also does estate sales and this is how it ended up in that channel.

 

I'm not complaining about getting a 9 inch gear! lol.gif In fact, the other day I was wondering if I should have went with a slightly larger gear than 7.5 inch.  I guess I did even though I didn't know it at the time.

 

Hopefully I'll be starting a new thread sometime before too long documenting the mount build.


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#14 Toups

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Posted 18 December 2020 - 02:08 PM

IMO it is important to use a compliant mechanism as the hinge or pivot when spring loading the worm against the worm gear. This is because the movement is going to be very very small and pivot stiction could cause the worm not to linearly follow the  movement (stick slip) caused by runnout of both the worm and worm gear bearings  and/or machining inaccuracies.  Byers minimized that BTW. My plan is not to pivot but to use a parallel leaf-spring flexure made with BeCu sheets attached to the bottom of the worm block. 

 

Don
 

Don, FWIW, the single ended mounted worm gear has a built in pivot and spring as mentioned in the instructions posted by MessyOne.



#15 Messyone

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Posted 18 December 2020 - 04:18 PM

Is there information sheet on the clutch mechanism?

 

Thanks!

Do you mean the six bolts and springs or the spring loaded adjustment on the worm gear?



#16 Toups

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Posted 18 December 2020 - 06:19 PM

The six bolts and springs that allow the hub to turn independently of the shaft. 

 

I assume your post has all the information that was distributed regarding the spring on the worm gear, but if there is more, I'm interested.



#17 Lola Bruce

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Posted 18 December 2020 - 06:25 PM

The grease you mentioned is dampening grease, just about the worst possible that you could use.


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#18 Messyone

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Posted 19 December 2020 - 02:22 AM

The 6 bolts are tightened just enough for the motor to work nad be able to move the scope.

 

As for grease can Lola Bruce please expalin why lithium grease I mentioned is the 'worst' 

 

My experience over the last 4 years is that it works very well.



#19 Toups

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Posted 19 December 2020 - 08:13 AM


<SNIP>

4) Lubricate or dry?  If not dry, would HELIMAX-XP Camera Telescope Optical Instrument Focusing Helicoid Grease w/ PTFE be a good candidate?

<SNIP>

 

The grease you mentioned is dampening grease, just about the worst possible that you could use.

 

 

<SNIP>

As for grease can Lola Bruce please expalin why lithium grease I mentioned is the 'worst' 

 <SNIP>

Messyone, I think the reference is to my question of using a helicoid camera grease and not your lithium grease suggestion.

 

I understand the objection to helicoid grease but a few excerpts from it's sales sheet are:

HELIMAX-XP Contains Lithium Stearate (Lithium "Soap") and sub-micron PTFE for superb lubrication in a light and clean formulation perfect for helicoid service.

 

The consistency of HELIMAX-XP™ is NLGI 1 (National Lubricating Grease Inst. Grade #1).

 

HELIMAX-XP™ provides maximum lubrication with minimal drag

HELIMAX-XP™ has a service range of -40ºF to +300ºF (-40ºC to +149ºC).

Those are some features that appear to be appropriate BUT not sure how "thick or damping" it is.  If it forms too thick a layer then it will add error.  Since it is designed for helicoids it probably forms way too thick of a layer.
 


Edited by Toups, 19 December 2020 - 08:15 AM.


#20 don clement

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Posted 19 December 2020 - 05:55 PM

Don, FWIW, the single ended mounted worm gear has a built in pivot and spring as mentioned in the instructions posted by MessyOne.

The pivot is not a stictionless compliant pivot as shown by  Russell Porter as item B. As I said the movement between the worm and worm gear is going to be on the order of microns (if built well) and is going from near zero velocity so the stick slip stiction of a non-compliant pivot will be factor IMO. 

 

Don

 

porterwormweb_zpsc944e035.jpg


Edited by don clement, 19 December 2020 - 05:57 PM.

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#21 don clement

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Posted 19 December 2020 - 09:49 PM

Pics of the clutch.

 

Don

 

IMG_6400Web.jpg

 

IMG_6405Web.jpg

 

IMG_6409Web.jpg

 

IMG_6410Web.jpg

 

IMG_6411Web.jpg

 

IMG_6412Web.jpg

 

IMG_6414Web.jpg

 

IMG_6415Web.jpg

 

IMG_6416Web.jpg

 

IMG_6417Web.jpg


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#22 TxStars

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Posted 19 December 2020 - 11:28 PM

A good quality grease is fine for the gears, but the clutch faces and disks should be clean and dry.


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#23 don clement

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Posted 19 December 2020 - 11:49 PM

A good quality grease is fine for the gears, but the clutch faces and disks should be clean and dry.

I am going to replace the Nylon slugs in my clutch assembly with self-lubricating Turcite. 

 

Don


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#24 Toups

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Posted 21 December 2020 - 10:38 PM

The pivot is not a stictionless compliant pivot as shown by  Russell Porter as item B. As I said the movement between the worm and worm gear is going to be on the order of microns (if built well) and is going from near zero velocity so the stick slip stiction of a non-compliant pivot will be factor IMO. 

 

Don

 

attachicon.gifporterwormweb_zpsc944e035.jpg

Yes, flexure hinges/bearings have lots of nice properties.  Lack of stiction is high on the list.  For nanopositioning they are in a class all of their own. Certainly seem a good fit for this application also. 

 

I'll add this to the list of future improvements but the first order of business is to build a pillow block flange bearing mount.  Improvements have to come after at least an initial working build.


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#25 Toups

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Posted 21 February 2021 - 08:59 PM

Have made enough progress on the design and build of a mount to use this gear that I have started a thread here. https://www.cloudyni...ild/?p=10900867 Few details have been posted, but will add more over time.


Edited by Toups, 21 February 2021 - 09:00 PM.



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