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getting out a blind hardened dowel pin...suggestions?

implmex

Diamond
Joined
Jun 23, 2002
Location
Vancouver BC Canada
Good morning All:
OK, I'm on the Porsche project again...this time the challenge is to separate a gear from it's shaft.
This is part of the windshield wiper gearbox.

There is a dowel pin holding them together.
It's 2 mm diameter and it turns out it's 10 mm long
You'd think they'd make it so you can just drift the pin out, but no...it's blind ended and on an angle.
It's also hard enough that I failed, trying to just drill it out on the Bridgeport.

I ended up having to burn it out on the sinker...a right royal pain in the ass!
I eventually got the remnants out, but now I have another one to do and it was a real crap shoot getting the trode aligned even reasonably well.

Have any of you discovered a magic bullet for a problem like this one?
I've heard of drilling and tapping dowel pins and putting in a Zerk to pump them out with grease, but for a 2 mm dowel, obviously this is a non starter.

I'm tempted to just cut off the shaft at both ends and bore it out, sacrificing however many carbide cutters I need to in order to chew up the hardened dowel.
I need to replace the shaft with a bigger one anyway, so it can be sacrificed...I just hate the thought of fucking up a bunch of cutters and boring bars to munch my way through the dowel.

I can then drift out the one side but that still leaves me with the remnant in the blind ended side, and now I don't have a convenient handle to hang onto the gear, so fixturing is more of a PITA if I decide to burn out the blind ended side so the gear can have a pin to support it on both sides like the original.

Here are pictures:
DSCN5788.JPG
DSCN5789.JPG

Here is the dowel remnant...you can see I didn't get the alignment very nice, so I scarfed up some of the bore that the dowel goes into.
It's not great, but I'll open it up enough to put in a custom sized pin, or I might just get lazy and laser weld the gear onto the shaft:
DSCN5790.JPG

Let me know anyone, if you have a brilliant solution I haven't thought of, to get that shitty little pin out on the second gearbox.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
Good morning All:
OK, I'm on the Porsche project again...this time the challenge is to separate a gear from it's shaft.
This is part of the windshield wiper gearbox.

There is a dowel pin holding them together.
It's 2 mm diameter and it turns out it's 10 mm long
You'd think they'd make it so you can just drift the pin out, but no...it's blind ended and on an angle.
It's also hard enough that I failed, trying to just drill it out on the Bridgeport.

I ended up having to burn it out on the sinker...a right royal pain in the ass!
I eventually got the remnants out, but now I have another one to do and it was a real crap shoot getting the trode aligned even reasonably well.

Have any of you discovered a magic bullet for a problem like this one?
I've heard of drilling and tapping dowel pins and putting in a Zerk to pump them out with grease, but for a 2 mm dowel, obviously this is a non starter.

I'm tempted to just cut off the shaft at both ends and bore it out, sacrificing however many carbide cutters I need to in order to chew up the hardened dowel.
I need to replace the shaft with a bigger one anyway, so it can be sacrificed...I just hate the thought of fucking up a bunch of cutters and boring bars to munch my way through the dowel.

I can then drift out the one side but that still leaves me with the remnant in the blind ended side, and now I don't have a convenient handle to hang onto the gear, so fixturing is more of a PITA if I decide to burn out the blind ended side so the gear can have a pin to support it on both sides like the original.

Here are pictures:
View attachment 431318
View attachment 431319

Here is the dowel remnant...you can see I didn't get the alignment very nice, so I scarfed up some of the bore that the dowel goes into.
It's not great, but I'll open it up enough to put in a custom sized pin, or I might just get lazy and laser weld the gear onto the shaft:
View attachment 431320

Let me know anyone, if you have a brilliant solution I haven't thought of, to get that shitty little pin out on the second gearbox.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
Nothing to it, tig a nut to it and use a slide hammer.
 
Hi moonlight machine:
That's actually a really good idea.
I wonder how tight those dowels are actually in there.
If they're not a press fit maybe I can laser weld a stub on and then use a dental slide hammer (for removing crowns) to pop it out.

I didn't even think of pulling it...I thought more of drilling it away.
I was a dentist too...pulling things should be like second nature to me.
I have no excuse :nono:

There are smart guys everywhere on this forum...thanks a bunch for pointing me in a new direction.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
I've seen people do it with stripped bolts also, tig/laser a nut on them and unscrew them.
slide hammer'n I would think would be your best other than edm.

Like you said, I have always had to carbide drill and tap, but 2mm:scratchchin:

You were a Dentist, just use your root extraction tool:D
1709413095332.png
 
Us tool and die guys have ran into similar, a goof ball thing I have done in past was.
mill/drill an angled hole down into the part and the pin, then using similar technique to a dental elevator, I put the tip in the pin and use the part as the fulcrum.
once pivot is maxed, I drill another hole in the pin, rinse and repeat, good times.

Then I go and wring the neck of the mold operator that sheared the pin off.
 
There are slide hammer adapters that hold collets for dowel removal. Dad bought one from Snap On for removing dowel pins from flywheels years ago. But there has to be a small amount sticking up to grab.
 
There are slide hammer adapters that hold collets for dowel removal. Dad bought one from Snap On for removing dowel pins from flywheels years ago. But there has to be a small amount sticking up to grab.
yeah if there was anything sticking up, I just use some flush cuts, bite and pivot.
 
Gotta ask again: why is this guy wasting your time? A quick search on eBay shows numerous options available. Is this some priceless, early-only gearbox that has a unique casting or something?
 
I would just drill a small hole from the blind side and tap it out. It's just a wiper gear, a hole through a tooth won't matter, or you can always weld it up and file it back to shape.
 
Hi Donkey Hotey:
I didn't ask...The customer has been restoring these cars forever and he knows exactly what he wants and why.
I don't second guess him...he's been a great customer and I'm happy to make whatever he asks for.

I get these odd little challenges occasionally, not too different from those I get rebuilding injection molds and modifying surgical instruments and all the other weird and wonderful stuff I like to do, now that I care more about enjoying the experience than about making a pile of money.

Superbowl, that would be a great idea but...I just put a file to the gear and it's hardened...I'm guessing in the mid 40's to low 50's RC, so If I were to drill it, it'd have to be with the sinker.
Seems weird to put a hard pin into a hard hub, but it is what it is...German engineering at its finest.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
A 2MM pin in ANY part of an auto speaks of lousy design. Maybe if it was part of the clock, or speedo or tach....but that's about it.

I don't have any great ideas on how to get it out...but I fully support the idea of not going back together with it.
 
Ceramic tube ( can be salvaged from heaters) or quartz glass from a lamp, a plain steel rod in a tig torch, slide down tube after a shot or argon into the sleeve.
Strike arc melt and push to short circuit cut power.
Remove sleeve, grip prong with slide hammer, thud.
A stud welder works just fine too but both may take a few attempts!.
Mark
 
Seems weird to put a hard pin into a hard hub, but it is what it is...German engineering at its finest.
Quite common in the auto industry. I have just sourced and supplied 500 4.08 mm +-.002 mm through hardened dowel pins for my steering rack client. They are used in the pinion assembly and start at 4 mm originally but after a few rebuilds they are now 4.08 mm.
 
There's a world of difference between 4MM and 2 MM when it comes to pins and dowels....more than 2MM!
 
There's a world of difference between 4MM and 2 MM when it comes to pins and dowels....more than 2MM!
Are you actually as stupid as you come across or is it a front. I was using a 4 mm * through hardened pin as an example there are plenty of 2 mm through hardened pins in auto assemblies.

*Note for idiots millimetre is not MM it's mm
 








 
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