Jump to content


Photo

Byers Nylatron Clutch Stiction, Lube?

  • Please log in to reply
15 replies to this topic

#1 bremms

bremms

    Mercury-Atlas

  • *****
  • Posts: 2528
  • Joined: 31 Aug 2012
  • Loc: SC

Posted 05 August 2014 - 09:17 AM

Hey everyone, I recently got my 1.5" shaft tap base pillow block mount up and running. I'm going to post some pictures and details soon. After the first outing the Byers all nylon drive has a good bit of stiction and even chatters a bit when moved.

Should I use some lube on the clutch? Some superlube maybe? I have some Krytox, but it's a bear to remove. What is a good lube for the worm? Guess I could e-mail Ed, but thought there might be some good ideas here.



#2 hottr6

hottr6

    Vanguard

  • *****
  • Posts: 2321
  • Joined: 28 Jun 2009
  • Loc: 7,500', Magdalena Mtns, NM

Posted 05 August 2014 - 03:07 PM

Not sure what you are talking about without photos ("...Byers all nylon drive" - what, even the worm is nylon?????).  I have a Byers 812, and there is no grease on the clutches.  Chatter does occur if the axes are not balanced.


Edited by hottr6, 05 August 2014 - 03:07 PM.


#3 bremms

bremms

    Mercury-Atlas

  • *****
  • Posts: 2528
  • Joined: 31 Aug 2012
  • Loc: SC

Posted 05 August 2014 - 07:12 PM

Sorry, the clutch is all nylon. I think the nylon is not stiff enough and it doesn't behave like the aluminum clutch with plastic pads. I have a smaller 7.1 starmaster and it has MUCH less stiction.

Attached Files



#4 bremms

bremms

    Mercury-Atlas

  • *****
  • Posts: 2528
  • Joined: 31 Aug 2012
  • Loc: SC

Posted 05 August 2014 - 11:47 PM

For some reason, the sticion and tightness got worse.  Took the drive off and the part of the clutch that attaches to the shaft is a way too tight fit in the drive gear,  it wasn't even seating in one area. May be partly deformation from the set screws and it is humid nylon may swell since it is hygroscopic.



#5 Chuck Hards

Chuck Hards

    Fly Me to the Moon

  • *****
  • Moderators
  • Posts: 5276
  • Joined: 03 May 2010
  • Loc: The Great Basin

Posted 06 August 2014 - 06:45 AM

Maybe you could machine, or route, shallow grooves in the clutch faces, to reduce the surface area.   Perhaps a radial or concentric pattern, possibly both as needed.



#6 hottr6

hottr6

    Vanguard

  • *****
  • Posts: 2321
  • Joined: 28 Jun 2009
  • Loc: 7,500', Magdalena Mtns, NM

Posted 06 August 2014 - 07:38 AM

Chatter does occur if the axes are not balanced.

Sorry, I thought you were referring to chatter between the worm and gear, which I notice when the payload is not balanced around the polar axis. Ignore my comments.

#7 bremms

bremms

    Mercury-Atlas

  • *****
  • Posts: 2528
  • Joined: 31 Aug 2012
  • Loc: SC

Posted 06 August 2014 - 08:56 AM

The problem is the use of Nylon for the mechanical parts. It swells and contracts with humidity and has 4 times the expansion of aluminum. I do realize it was easy for Ed to machine these parts out of nylon but it is a poor material for this application. I would have paid a good bit more for aluminum with plastic pads. The clutch was OK in the winter at low humidity and temperature. I had it at about 85 degrees and that thing was locked up. Machining a bit of clearance today

Clearance is between the shaft collar/ front plate piece and the inner bore of the main gear ring. At 70 deg clearance is tight at 80 deg it is locked up.


Edited by bremms, 06 August 2014 - 09:46 AM.


#8 Chuck Hards

Chuck Hards

    Fly Me to the Moon

  • *****
  • Moderators
  • Posts: 5276
  • Joined: 03 May 2010
  • Loc: The Great Basin

Posted 06 August 2014 - 09:50 AM

The 8" Byers drive on my Astrola has aluminum clutch parts.  I wonder when Ed made the switch?  



#9 sglamb

sglamb

    Explorer 1

  • -----
  • Posts: 65
  • Joined: 10 Jul 2008
  • Loc: Florence, KY

Posted 06 August 2014 - 10:47 AM

I have several of the Byers drives with the nylon hubs and they all had the same behavior.  I thought it was a temperature related problem because they always tightened up around 85 degrees - sometimes even seizing.  I "fixed" them by taking off some of the nylon using V grooves so that the overall diameter was retained.  It works for now but I hope there's not too much slop come this winter.

 

Steve



#10 bremms

bremms

    Mercury-Atlas

  • *****
  • Posts: 2528
  • Joined: 31 Aug 2012
  • Loc: SC

Posted 06 August 2014 - 11:47 AM

I just machined 0.003 off the flange and it's not binding at 85 deg. Tiny bit of play. At 40 degrees this winter it I'll be a sloppy fit. If I get really bored soto speak I can machine a hub from Aluminum

#11 bremms

bremms

    Mercury-Atlas

  • *****
  • Posts: 2528
  • Joined: 31 Aug 2012
  • Loc: SC

Posted 06 August 2014 - 11:52 AM

It was completely bound at 75-80 degrees before and tight at 70. In the winter the Nylon will shrink due to change in humidity and temperature.

#12 bremms

bremms

    Mercury-Atlas

  • *****
  • Posts: 2528
  • Joined: 31 Aug 2012
  • Loc: SC

Posted 06 August 2014 - 12:31 PM

OK I did some back of the envelope calcs and here it goes The difference in coeff. of expansion Al to Nylon is ~70x10-6 mm/mm per degree C

The hub is about 120mm wide gives 8.4x10-3 mm/Deg  say a 20 degree difference summer to winter. 0.168mm!!!  0.0066"  That is a problem.

 

Put the drive in the car 106 F with the infrared gun.  Locked up tight! At least it's OK at 90 deg.


Edited by bremms, 06 August 2014 - 02:23 PM.


#13 herrointment

herrointment

    Skylab

  • *****
  • Posts: 4362
  • Joined: 12 Mar 2011
  • Loc: North of Hwy. 64

Posted 06 August 2014 - 03:36 PM

I'll be....learn something new all the time here. That nylon would move that much (or at all) !



#14 bremms

bremms

    Mercury-Atlas

  • *****
  • Posts: 2528
  • Joined: 31 Aug 2012
  • Loc: SC

Posted 06 August 2014 - 04:29 PM

Most plastics have high expansion coefficients. Large parts will have large dimension( relatively) changes with temperature.

Another picture of the mount.

Attached Files



#15 herrointment

herrointment

    Skylab

  • *****
  • Posts: 4362
  • Joined: 12 Mar 2011
  • Loc: North of Hwy. 64

Posted 06 August 2014 - 08:02 PM

I need to do some reading. I've been under the assumption that plastics are the unmovable force.....then again, I'm a woodworker!



#16 bremms

bremms

    Mercury-Atlas

  • *****
  • Posts: 2528
  • Joined: 31 Aug 2012
  • Loc: SC

Posted 06 August 2014 - 09:47 PM

Test pic from phone








Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics