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The RA Motor on my G-11 is so loose that I have to slap it back into position in order for it to engage the gears.? I don't see any way to "tighten" it so it doesn't wobble in and out of the housing.? I fear I damaged something by incorrectly transporting the mount sitting on the motor.? Does anyone know the correct fix for that?? Photo shows the motor in the "out" position.?
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On Thu, Mar 27, 2025 at 09:33 PM, David Woolf wrote:
The RA Motor on my G-11 is so loose that I have to slap it back into position in order for it to engage the gears.? I don't see any way to "tighten" it so it doesn't wobble in and out of the housing.? I fear I damaged something by incorrectly transporting the mount sitting on the motor.? Does anyone know the correct fix for that?? Photo shows the motor in the "out" position.?
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Hi David, you probably stripped the thread that the motors screws screw into. That's not hard to do, these threads are plastic.
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You can try to repair the threads with some adhesive (something that's designed to bind metal and plastic), use a slightly larger diameter screw, or do what I did. I used the other screws that go into the metal cover, unscrewed them, put a fairly wide, rust-proof washer on them, then screwed them back in. The washers press on the front lip of the motor, keeping it pressed into the gearbox and stopping it from moving. And these screw into metal, so are much harder to strip :) YMMV.
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David. ?
The motors are held against the Plastic gearbox by UNC 4-40 screws. ?Constant removing, reinstalling or over tightening of these screws damage the plastic threads. ?Easiest fix is to replace the gearbox and be aware of this issue.?
A better fix would be trying plastic welding the gearbox or adding some type of nutsert inter the rear of the gearbox front plate. ? Which means splitting the gearbox and working out a way to try fit a small thin plated tapped to suit or one of those plastic nut inserts. ? Something that doesn’t interfere with the gears. ? Then use M2 long screws to reassemble and secure the gearbox together.?
One user, a while back cut a hole in the rear of their gearbox so they can see and adjust the pinion mesh better. ?Which I think was a good idea if you disassemble and repair the Gearbox?
FWIW
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CHEERS
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Brendan
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Could you repair plastic threads by putting a bit of plastic cement (glue) into the threads, letting it harden, and then letting the screw cut new threads into it?
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On Fri, Mar 28, 2025 at 05:05 AM, <davidrico13@...> wrote:
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Not very effective in most plastics especially a thin plastic part like this.? The best route I have found is to replace the gearboxes with a new one.? Or alternatively use common thread adhesive or a piece of thick dental floss on the hole as the standard fastener is screwed in, (it can take two lengths in the hole for the threads to get good purchase) as an emergency fix while you wait for new gearboxes.? The gearboxes are pretty durable if you are careful when staring the fasteners but they tend to be sort of a wear item for those who disassemble their mounts often.? Stock a spare.? ?
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Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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On Fri, Mar 28, 2025 at 07:11 AM, Michael A. Covington wrote:
Could you repair plastic threads by putting a bit of plastic cement
(glue) into the threads, letting it harden, and then letting the screw
cut new threads into it?
The gearboxes are a slightly soft plastic so regular plastic glue that melts the plastic to form a bond probably won't work.? The heavy dental floss does work and you can adjust how much you use to get a tight mechanical connection.? I wouldn't count on it as a permanent solution but it seems to work pretty well.? I like the plain stuff but if you like a minty fresh mount pickup the mint flavored stuff.? ?
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Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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Lots of videos on FB/You Tube? on repairing plastic. I generally heat weld plastic to fill the stripped hole and reinforce with fine metal screening that either epoxied or melted in to the plastic. Drill and rethread. $4-40s are a bit light for this purpose and given the size of the structure I'd Try some 3mm screws they are 0.1133" just a bit larger than the #4"s 0.1120". 3.5mm gets you up in the same territory as #6.
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I disagree with the idea that a thread repair solution like a Helicoil is not effective. The approximately doubling of the screw to female thread engagement area makes for a very much stronger fastening. There are several alternative systems on the market but the Helicoil design is probably more likely to be available at any decent sized fastener store. The required inserts, insertion tool and tap is not a five and dime purchase but compared with a replacement motor it is a bargain. And fix all of them while you are at it. Be proactive.
For what it is worth, when I build apparatus for highly stressed environments such as racing cars and aviation related designs, I build thread reinforcements of some sort into the design.
Mike
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On Sat, Mar 29, 2025 at 06:25 PM, Mike Colyar wrote:
I disagree with the idea that a thread repair solution like a Helicoil is not effective. The approximately doubling of the screw to female thread engagement area makes for a very much stronger fastening. There are several alternative systems on the market but the Helicoil design is probably more likely to be available at any decent sized fastener store. The required inserts, insertion tool and tap is not a five and dime purchase but compared with a replacement motor it is a bargain. And fix all of them while you are at it. Be proactive.
For what it is worth, when I build apparatus for highly stressed environments such as racing cars and aviation related designs, I build thread reinforcements of some sort into the design.
Mike
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Mike,
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Where applicable Helicoil threaded? inserts are an excellent solution for many metal thread repairs.? I have used them for decades in street and track car chassis repairs and modifications as well as alloy cylinder heads, blocks etc.??
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Where applicable are the key words.?
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Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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Yes, but in this design there's really?no material to take advantage?of the helicoils strengths. It can only thread into the same plastic.?
A good quality stainless 4-40 has a yield?strength of 120 pounds. A 0.112 4.40 tapped hole in 16 ga. ABS has about 60 pounds. No more than 1 in-lb. torque on the screw is recommended.?
I've used heat set threaded inserts and they work well with less chance of breaking the plastic. Problem is I've had about 3/16th" plus thick plastic to set them in. The gear housing doesn't look that heavy. However, I came across this you tube, which offers a solution.
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On Sun, Mar 30, 2025 at 06:21 PM, George Cushing wrote:
However, I came across this.....
I'm not sure of any material advantage exists for not just replacing the part, given this new part exists and installed with fewer unknowns.? But that reference link for repair of plastic coverings is a wonderful resource to keep in mind.
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Losmandy assembly should really use Paul's Safety Clips to help prevent the issue.? And sell a modified short motor hex key tool for these motors.? Something that fits straight in, limits torque, and costs $1 but sells for $5 to help with the stocking overhead.
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Thank you,
Doug
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On Tue, Apr 1, 2025 at 08:17 AM, WayBack wrote:
On Sun, Mar 30, 2025 at 06:21 PM, George Cushing wrote:
However, I came across this.....
I'm not sure of any material advantage exists for not just replacing the part, given this new part exists and installed with fewer unknowns.? But that reference link for repair of plastic coverings is a wonderful resource to keep in mind.
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Losmandy assembly should really use Paul's Safety Clips to help prevent the issue.? And sell a modified short motor hex key tool for these motors.? Something that fits straight in, limits torque, and costs $1 but sells for $5 to help with the stocking overhead.
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Thank you,
Doug
What are "Paul's Safety Clips" what do they do?
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Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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On Wed, Apr 2, 2025 at 11:16 AM, Chip Louie wrote:
What are "Paul's Safety Clips" what do they do?
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On Wed, Apr 2, 2025 at 11:16 AM, Chip Louie wrote:
What are "Paul's Safety Clips"
Chip the comment referred to the earlier comment on this thread.? Where Paul mentioned using a washer as a clip hold the motor flange against the housing.? Preventing stress on the mounting bolts either before or after repair becomes a requirement.
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And the waxed dental thread material for damaged threads also something worth remembering.?
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On Thu, Mar 27, 2025 at 10:36 PM, Paul Kanevsky wrote:
I used the other screws that go into the metal cover, unscrewed them, put a fairly wide, rust-proof washer on them, then screwed them back in
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Doug
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David Woolf
Paul Kanevsky
Chip Louie