Mascot Precision Tools Adjustable Gear/Wheel Puller

[Maletrain]

OK, you guys have convinced me that I need to be able to re-gauge wheels if I want to use Atlas N scale Code 55 track and do operations.  So I bought one of these things:
https://www.therailwire.net/forum/gallery/2700-120717041959.jpeg

When it arrived, I was dismayed to see that the "business" part, the "ram", was bent out of "true" with the axis of rotation.  It is about 1/16" in diameter, and Peteski has already posted that I need to grind it down to about 1/32" diameter to work on N scale wheels.  I can straighten the pin enough to work, and I can grind down the diameter.  But, I am concerned that's such a thin pin might not be strong enough to resist being bent out of "true" pretty easily, given that it is not so strong to begin with at 1/16".

I am wondering if this pin is easily removed.  The whole part seems to have been plated as one piece, so I am not sure how the pin is attached to the end of the part with the screw threads.  If I could pull it, I would replace it with dill rod of the same diameter, and perhaps have a set of replacements that I could interchange, each with a different "business end" diameter to suit the axel shaft I wanted to push with it.

Has anybody done that?  Looking to learn from others' successes (and mistakes) so I don't have to start on the toe of the learning curve with my own mistakes.

[Lemosteam]

If its soft- its soft.

Go buy a matching thread grade 8 socket head screw long enough to do the job, chuck it in a drill and use a dremel with a cutoff wheel parallel to the axis of the screw and rotating against the rotation of the drill press, slowly grind down the end until you achieve the diameter you want.  you may want to taper the cut out to the OD as opposed to a hard shoulder, to prevent the pin from snapping off if it encounters a slight angle.

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[Maletrain]

It seems to be a common 10-32 thread, so there are plenty of grade 8 screws around to do what you suggest.

But, I still think that a more elegant solution is to just have replaceable pins.  They only need to work under compression, so there is no need for more than a slip-fit into the hole in the threaded ram.  And, it is much easier to adjust the diameter of a small pin than to start with a #10 grade 8 bolt. 

One of the issues with using a ground-down bolt is to make sure that the "pin" ends-up concentric with the threaded shaft.  Bolt heads  and the outside surfaces of nuts are usually not exactly concentric with the threads, so gripping the bolt head is not the way to do the rotation for grinding, and gripping the threads without removing the bolt head can also be a problem with the tools at my disposal.

So, still looking for someone with experience modifying the part that came with the tool.

[peteski]

I have no problem with the original ram pin (ground down to a smaller diameter) bending on me. I also like the idea of having replaceable pins. I was thinking of using either piano wire or high speed steel rods (both available on eBay and probably lots of other places).  IIRC it is either 1.5 or 2mm in diameter.

[Lemosteam]

I have no problem with the original ram pin (ground down to a smaller diameter) bending on me. I also like the idea of having replaceable pins. I was thinking of using either piano wire or high speed steel rods (both available on eBay and probably lots of other places).  IIRC it is either 1.5 or 2mm in diameter.

I never mentioned to grab the bolt head. I should have explained that I ground down the head to the OD of the thread, and then flipped the bolt around and ground the pin concentric to the OD.

A hardened long set screw with would eliminate this step.


If you have the ability to drill into hardened threaded bolts, go for it.  If you use a soft bolt the pin will just deform the bottom of the hole.

The piece to use is a cylindrical bearing pin if you go this route.

[peteski]

To me it seems that you guys are overthinking this.  Like I said, I used the stock ram pin and have not noticed any bending or deformation. The wheels aren't that tightly pressed onto the axles, and even if the screw is a little lose, it seems to  be helpful in aligning the puller to the axle.

[Lemosteam]

To me it seems that you guys are overthinking this.  Like I said, I used the stock ram pin and have not noticed any bending or deformation. The wheels aren't that tightly pressed onto the axles, and even if the screw is a little lose, it seems to  be helpful in aligning the puller to the axle.

@peteski The OP mentioned his ram came non-concentric.

[peteski]

@peteski The OP mentioned his ram came non-concentric.

You're right.
Well, he should return it and get a better-made example.  The stock ram pin is hard (and stiff enough  ) for its intended purpose.  I forgot to mention that it is press-fit into the hole in the screw, then the assembly was plated. I pulled it out to grind down its diameter.

[Maletrain]

I tried pulling the pin, but maybe not with enough force, because I did not want to break it off inside the hole. So, Peteski, how did you pull yours?  If I can do that, it will save me a lot of work, because I can then replace it with a variety of other pins that have reduced diameters on one end to match any task.  All of the new pins would be fitted to the hole so as to have just a slip-fit, so that they could be easily replaced as various tasks demanded, or if I bent one.

[peteski]

I tried pulling the pin, but maybe not with enough force, because I did not want to break it off inside the hole. So, Peteski, how did you pull yours?  If I can do that, it will save me a lot of work, because I can then replace it with a variety of other pins that have reduced diameters on one end to match any task.  All of the new pins would be fitted to the hole so as to have just a slip-fit, so that they could be easily replaced as various tasks demanded, or if I bent one.

I don't remember how I did it.    I think that I clamped the pin in a vise leaving a gap space between the shoulder of the screw and the jaws of the vise to slip a lever, the used either needle-nose pliers or a pair of mall dikes as a lever to pry the screw upwards freeing the pin.

[rrjim1]

I manufactured tools for HO slot cars and when making a puller with a harden pin in the screw I used Loctite retaining compound to hold the pin. If this is what is holding the pin you might try a little heat while trying to remove it.

[peteski]

I manufactured tools for HO slot cars and when making a puller with a harden pin in the screw I used Loctite retaining compound to hold the pin. If this is what is holding the pin you might try a little heat while trying to remove it.

My 2 pullers had the pin simply held by friction (no traces of any retaining compound on them).  Kind of like when a worm is press-fit onto a motor shaft.

[Maletrain]

My pin is being really stubborn.  I first tried putting penetrating lubricant on the pin/ram junction, then threading the ram into some 10-32 nuts to hold it in a vice and locking vice grips on the pin, then tapping the pin with a small hammer.  Nothing.  I then tried using a lever between the vice and vice grips - still nothing. So, I tried heating the pin with a soldering iron and levering again, still no movement. 

I will have to wait until I can get to my shop to use a torch on the pin, and I don't know when that is going to happen.  At least I convinced myself that the pin won't break.  But, I have now scarred it too much to return this thing.   So, I either need to get that pin out of it or I will need to make an entirely new ram with a concentric center hole and at least one new removable pin with a 1/16" shank and a 1/32" business end.

[rrjim1]

My pin is being really stubborn.  I first tried putting penetrating lubricant on the pin/ram junction, then threading the ram into some 10-32 nuts to hold it in a vice and locking vice grips on the pin, then tapping the pin with a small hammer.  Nothing.  I then tried using a lever between the vice and vice grips - still nothing. So, I tried heating the pin with a soldering iron and levering again, still no movement. 

I will have to wait until I can get to my shop to use a torch on the pin, and I don't know when that is going to happen.  At least I convinced myself that the pin won't break.  But, I have now scarred it too much to return this thing.   So, I either need to get that pin out of it or I will need to make an entirely new ram with a concentric center hole and at least one new removable pin with a 1/16" shank and a 1/32" business end.

Heating the pin will expand it making it tighter in the screw. Heat the screw as quick as possible that should expand the screw and melt any compound if used, releasing the pin. 

[Maletrain]

It is practically impossible to differentially heat the screw and/or cool the pin enough to get differential thermal expansion to release the pin. They at both metal and in contact over a significant depth, so heating or cooling one is going to do the same to the other before the whole length of the hole is heated or cooled.   My reason for wanting to use a torch on the pin is to make sure I have adequately "cooked" any lock-tite in the hole, in hopes that will release the pin.