spirol Pin Removal from Blind Hole 4

[Finglas]

What’s the best way of removing a spirol from a blind hole? The current procedure is to tap into the spirol pin and just pull the tap upwards in the hope that it will have enough grip on the spirol pin. Are there an specific tools for the job?

 

[asimpson]

Cant think of special tool.

Can you bore it out 1 or 2 mm less than pin diameter? Excess material could then be removed by hand as pin pressure on bore is reduced.

I would be worried tapping and putting in screw would increase pin holding pressure.

 

[btrueblood]

I'd not use the tap as the puller, the material is brittle and will break if bent, it provides a poor gripping surface at the threads due to the cutting flutes, and it provides a poor gripping surface for pliers or whatever you are using to pull on it with. Get a (long as possible) machine screw to fit the tapped hole. Machine a small circular weight to slip over the screw, and use it to gently tap against the head of the screw to back the pin out. Similar tool is used to remove the press-in plugs/orifices etc. for hydraulic circuits, e.g. Lee company.

 

[btrueblood]

Sorry, one last point. If this is a pin that often needs to be removed, suggest getting a dowel pin with a pre-threaded inside. If the roll pin must be used, suggest chucking in a lathe and pre-threading the i.d.

 

[hydtools]

Maybe try hydraulic removal. Fill the ID about half full of oil. Use a drive pin that fits the ID of the spring pin. Give the drive pin a hard hit with a hammer to force the spring pin out.

Ted

 

[RebelBrill]

What is the pin diameter, length, and material?

 

[Wrenchbender]

Your present procedure, with a taper tap sounds the most feasible. If the pin is flush with the surface, you could also place a nut on the pin. Plug weld the nut to the pin. Now you have something to grab. Yes, I know, you shouldn't weld hi-carbon steel, etc., but this is an emergency procedure I assume.

 

[Compositepro]

My two cents: Place a nut on the tap first, then tap into the pin for adequate grip. Screw the nut down to pull the pin. Use a larger nut for a spacer to pull the pin up past the surface.

An alternative would be to just drill out the pin. You may need to do some drilling anyway to allow for a tap to get a grip.

 

[ajack1]

If you can tap the pin then use a slide hammer, you can easily make one if you have access to a basic machine shop. The link should give you a good start.

 

[dinjin]

I think what you are doing is the most common approach to
removing the spirol pins. I have seen them often in the filler plugs in ball bearing designs, and often two of them, and the approach you are using is done in the field.
I think a tool could be made but it might be specific to a particular manufacturers pin design.

 

[MikeHalloran]

Hydraulic removal works great on anything that has a hole in the center, like rolpins, crankshaft pilot bushings, oilite bearings in starter motor endcaps, stuff like that.

... But I rarely use oil for it. Grease works better.

I also use bits of paper towel as pseudo-gaskets.

And a big hammer. Once you've bled out the air, it's just like hitting metal.

One big advantage of hydraulic removal; you can re-use all the parts if you need to, because it doesn't usually leave a mark or make a chip.



Mike Halloran
Pembroke Pines, FL, USA

 

[4JawChuck]

Slide hammer with a collet chuck attachment works like a charm.

 

[berkshire]

And if you bugger it up doing that, look at a tap removing EDM machine.
B.E.

 

[Finglas]

btrueblood> doesn't need to be removed too often. It's on a product that is assembled and after assembly runs through some tests. If certain tests fail it needs to be disassembled. Failure rate of about 1/10. Can you send on a link for a pre-threaded dowel?

 

[ajack1]

Google extractable dowels, you will find loads of suppliers.

 

[btrueblood]

Finglas,

Extractable dowel pins:

http://www.mcmaster.com/#dowel-pins/=ah2up6

As ajack says, there are a lot of suppliers besides the above, but Mcmaster ships (to my shop) next day typically, which is great for r&d.

The problem with "hydraulic removal" on a spirol (aka roll pin) is the slot up one side, the grease or oil just leaks right past it and you can't get enough pressure to budge the pin. My experience, yours may vary, and it may depend on the pin size.

 

[unclesyd]

If the roll pin is failing from shear/fatigue one quick method to improve the strength is to insert a small pin into existing pin.

 

[hydtools]

Install a headed extraction mandrel, head to the blind end of the hole, with the spring pin. If the pin does not need to be removed, cut off the mandrel. If the pin needs to be removed, pull the mandrel.

Ted

 

[rmw]

All this discussion of tapping the (hardened) pin assumes that it is tight enough in the hole to prevent rotation when torque is applied to the tap.

As to getting it out, all you need to get out is enough to be able to get a good grip on it with a set of vice grips. The vice grips not only grip the pin for pulling, but placed strategically, they also compress the pin which reduces the force needed to pull it. I've tapped on more than a few vice grips thusly attached to a roll pin I was trying to get out.

If I had the situation described in the OP, and it could be tapped, I'd tap it for a certain distance, say 50% of the length, and I'd then put a rod into the center of the pin, said rod being about 75% of the length (depth) of the pin and then I'd thread a hardened bolt into the threaded hole and thread it in until it contacts the rod and begins to jack against it which would and then back the pin out - hopefully enough to use the aforementioned vice grips.

Once you tapped the pin, it is junk anyway, so don't worry about what the vice grips do to it.

rmw

 

[dinjin]

I assumed you were using the spirol pin so you could relax the need of holding the hole size to a close tolerance.