bonding agent

[thomas81z]

ok im splicing together a dogbone for my steam driveline & i need

a glue/ bonding agent that will melt the plastic together .

who uses what interms of bonding plastics??

[tstage]

A couple of questions:

• Do you know what plastic the dogbone is made of?
• How do you plan to splice it to your drive shaft?  End-to-end (aka butt joint)?

Given the rotational and lateral forces on a drive shaft, even a two-part epoxy isn't going to hold up well if butt-jointed.  And most commercial drive shafts (e.g. NWSL) are made of delrin and adhesives do not adhere well to it.

Your best bet for mating two shafts will be mechanical - e.g. a sliding collar with set screws that can be tightened down onto the motor & drive shafts...or a whole new dogbone/cup/shaft combination designed specifically for your locomotive's motor shaft.  A photo and more specific information of what you are trying to accomplish would also be very helpful in how best to come up with a solution for your situation.

Tom

[gmpullman]

A-Line makes a handy kit that can repair some newer motor drives:

https://ppw-aline.com/products/12030-universal-joints-coupling-assortment

More here:

https://ppw-aline.com/collections/miscellaneous-re-powering-parts

 

And as Tom mentioned, NWSL is a good choice.

Good Luck, Ed

[Overmod]

Is this the actual dogbone, a shaft with two crossed universal pins at the ends, that is either broken in half or being assembled?

If broken, solvent welding may not be strong enough.  Tom's idea of a splicing tube is a good one; you might also use a split tube that fits the shafts either side of the break with two-part inside, then pin one end of a piece of thin elastomer tape to one half of the tube, apply adhesive compatible with the tape, and wind a few wraps under tension, holding it until all the adhesive is set or cured.

I would not expect any unreinforced butt joint to work.  You might be able to drill both broken ends to take a piece of wire reinforcement, but you'd have to carefully drill both concentrically and straight -- no mean feat! -- and then apply a blob of steel-reinforced two-part to play the part of the sleeve.  That might then have to be tooled to get rotating balance; that is a bit easier if the ends of the dogbone ahead of the universal pins are cylindrical.

The kit being suggested works a different way.  Only the parts on the motor and driven shaft ends would be 'glued'; the U-joints are spiders and the couplings to the crossed arms can 'float' on a splined driveshaft to accommodate any length change in traversing curves or tilting to level changes.  Here you would fux a broken shaft simply with a new length, not have to preserve 90-degree cross orientation as with a dogbone in one piece.

[richhotrain]

What brand and type of steam locomotive is it?

Rich

[railandsail]

I have 2 suggestions for you but I have to look them up a bit later as I need to run a few errands first.

1) Bondic....laser light cured adhesive utilized in the dental industry. Lots of info and testimonial on the internet.

2) Pasco Fix.....I have personal experience with this one, having discovered it at a boat show years ago. Its amazing what it will bond together.

[rbturner]

Shrink tubing.

[RR_Mel]

I like Randy’s shrink tubing, two layers would be better than one.
 

Mel



 
My Model Railroad   
http://melvineperry.blogspot.com/
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps

[Overmod]

RR_Mel

I like Randy’s shrink tubing, two layers would be better than one.

Be sure the dogbone halves are straight and reasonably 'concentric' first and test-fit or make a jig so you can align the joint 'blind'.  I think I would use a little adhesive on the break and press the joint together before shrinking the tubing.  On the other hand, as long as the universals stay reasonably crossed a little 'bending' or stretch in the repaired shaft might actually be useful... if it isn't turned fast enough under load to try to whip.

[selector]

I'm not sure what I am about to relate is in any way relevant, or helpful...

Wife and I moved 5 years ago and purchased a suite of 5 GE kitchen appliances new (it's the 'cost' of us moving when we do...wife gets new big stuff  ).  The stove/oven combo has five 'chromed' plastic knobs for the five stove-top elements.  They're crap.  They split at the mouth of the plastic well that fits over the stub pin protruding from the face of the panel.  I ordered a package of new ones, but it was gonna be the only time I intended to do that....ever.  Weren't cheap, neither, not for what you get.

My idea was to 'armor' (American spelling for ease of reading) those wells at their mouth ends so that they won't split.  I have no idea what the plastic is, or even if it can charitably be called plastic, but I know what two-part quick epoxy is.  I mixed a small dab of it on some foil and then gobbed it around those well-mouth ends in the shape of a collar. I suspended the items to help the collars to stay put and to keep their shape for about two minutes each while the 5-minute epoxy set.  I knew, from making epoxy lakes and rivers on the layout, to be darned good'n sure that the two components were equal in mass and that they were mixed very thoroughly...not just 20 swipes through them with a toothpick!  So, the epoxy was going to be tough and hard.

And it is, now about 18 months later.  None of them have split.  This might be a solution to the problem of strengthening these dog-bone components.

[doctorwayne]

tstage

...most commercial drive shafts (e.g. NWSL) are made of delrin and adhesives do not adhere well to it....

LePage and Loctite, and probably others, too, make a ca specifically for use with engineering plastics, such as Delrin.  It's a two-part solution, with a "prep" to be applied to both mating surfaces, and allowed to dry for 60 seconds.  Ca is then applied to one of the mating surfaces, and the two pieces brought together.

For using it on that driveshaft, I'd put lengths of tight-fitting brass tubing on both pieces, long enough to cover most of the shaft of each piece, with a somewhat shorter piece of brass tubing of the next larger size slipped onto one of the parts.

Prep the mating surfaces as directed, along with the exposed portions of the driveshaft, then apply the ca (any brand will work - it's not limited to the stuff which comes in the kit) and bring the two mating surfaces together, followed by quickly sliding the brass tubing together near the joint in the driveshaft.
The length of larger brass tubing can then be slid over the joint and fixed in place with ordinary ca.

This method should repair the intial break, and cementing the brass tubing to both portions of the rejoined shaft and then connecting them with the larger tubing should keep the whole shebang together, regardless of torsional forces when the loco is running.

Wayne

[jjdamnit]

Hello All,

Replacement over repair is probably your only long term solution.

If you have not corrected the situation that caused the part to fail, no adhesive or replacement will last.

I recently broke two replacement dogbone driveshafts because the gear tower was warped and caused the worm gear to bind and snap the shafts. I ended up replacing the entire gear tower along with a third dogbone.

When a fellow electrician would ask, "can I borrow your 'X' tool? I just broke mine." My first question was, "What were you trying to do when you broke it?"

Yes, you can drive a nail with a wrench, but why, when you should use a hammer.

I've tried to use metal sleeves to "repair" cracked worm gear couplings rather than replace them.

It was akin to fitting roller skates to a pig- -an utter waste of time and it only annoyed the pig.

Probably your best option, if you can't find a suitable replacement part from the manufacturer, is to look on auction sites for a used unit to cannibalize the part(s) you need.

Hope this helps.

 

[thomas81z]

jjdamnit

Hello All,

Replacement over repair is probably your only long term solution.

If you have not corrected the situation that caused the part to fail, no adhesive or replacement will last.

I recently broke two replacement dogbone driveshafts because the gear tower was warped and caused the worm gear to bind and snap the shafts. I ended up replacing the entire gear tower along with a third dogbone.

When a fellow electrician would ask, "can I borrow your 'X' tool? I just broke mine." My first question was, "What were you trying to do when you broke it?"

Yes, you can drive a nail with a wrench, but why, when you should use a hammer.

I've tried to use metal sleeves to "repair" cracked worm gear couplings rather than replace them.

It was akin to fitting roller skates to a pig- -an utter waste of time and it only annoyed the pig.

Probably your best option, if you can't find a suitable replacement part from the manufacturer, is to look on auction sites for a used unit to cannibalize the part(s) you need.

Hope this helps.

 

 

I agree , its the dog bone from a rivarossi big boy , he nwsl " universal kit" is to thick & not close

the f unit replacement from bachmann is close but still needs to

be cut to shorten it .

i will get a "junk " big boy from evilbay i find a ton or wrecked 1st gen big boy

/ challengers but not alot of 85ish & up ones with the newer drivetrain

but what sucks is

the 67 to 80 big boys are basically useless because they are

a totally diffrent animal.

[Overmod]

Incidentally, before this thread vanishes, if anyone is interested in alternatives for drivelines see

https://www.wmberg.com/products/couplings

Some of these can be 'homemade' with care.