Help getting the broken roll pins (on the Delta BS) out

[FredP]

is it possible to get to the underside and drill a small 3/16"? hole and use a drift punch to drive it out using this hole? cast iron drills fairly easily.

 

[shaf2376]

Okay if you are still trying to get the pin out here is the easy way. Since the block is cast and the pin is harden you can use a cutting torch. All you do is heat the pin and then hit the air to cut. It will cut out the pin and not damage the cast. You will have to "ream" out the hole with a drill once you are finished because it will have a little slag left in it from the pin. I have done this many times on camshafts that have a sheared pin in them and it works every time.

 

[fsdogwood]

I was thinking about this, I've drilled cast iron before, using HF drill bit, and found it soft. Not sure if this would make the upper arm weak, so a bit hesitated.

Well, tried to drill the "heated pin" (heated Monday) yesterday, with DeWalt cobalt drills from Lowes, and no-name carbide drills from Ace, saw some scratch,
but the pin did seem to be pushed in further, and the opening of the hole seems to have got a bit enlarged. Thus I stopped.

So heating at least make the pin movable, as on Sunday, I tried with punch and code chisel, and the pin didn't seem to move at all.

I may call the Delta/DeWalt service place to see if they have suggestion, think they are closed on weekends.
Or worst case, I'll drill from the underside and try to punch it out.

 

[fsdogwood]

Okay if you are still trying to get the pin out here is the easy way. Since the block is cast and the pin is harden you can use a cutting torch. All you do is heat the pin and then hit the air to cut. It will cut out the pin and not damage the cast. You will have to "ream" out the hole with a drill once you are finished because it will have a little slag left in it from the pin. I have done this many times on camshafts that have a sheared pin in them and it works every time.

Monday was the first time I ever used a torch, the mini-torch from HF. It might be a soldering one. What would be a "cutting torch"? Any link?
What does it mean to "hit the air to cut"? Will the cutting torch cut the pin only, but not the cast iron?

Appreciate your help

Pinwu

 

[shaf2376]

A cutting torch is an oxygen/acytylene torch used to cut metal. Hitting the air refers to the cutting operation and there is a lever on the torch you depress which blasts the oxygen and cuts/blows out the hot metal. A weld shop would have one and you can also rent one from some rental places. Someone on here near you may have one as well.

 

[Scott Kuykendall]

-What model saw do you have? I looked at a manual on Delta's web site and looked at the 28-206 or 28-276. Are they the two pins that hold the upper arm to the base, they show four pins two on each side. If that is them the best way is going to be drilling a small hole (1/8") through the bottom of the hole that has the broken dowel pins and tap them out with a small punch. I can't tell from the manual but it looks like it shouldn't hurt drilling a small hole there but do it at your own risk, since I can't see it. You will have to be able to get the drill straight under the hole and I don't know if you can. If there is some thing in the way you could use a 90 degree drill head http://www.harborfreight.com/3-8-eighth-inch-angle-drill-attachment-with-keyless-chuck-92188.html but then your just buying more stuff to try. You said the pin got driven farther down the hole, if you have enough room to put a shorter pin on top of the broken one and have it deep enough to keep the parts from turning. The bolt holds it tight, the pins are just to keep the two parts from twisting. If they are dowel pins you won't be able to drill the pins, they are very hard. Hope this helps.
Scott

 

[fsdogwood]

-What model saw do you have? I looked at a manual on Delta's web site and looked at the 28-206 or 28-276. Are they the two pins that hold the upper arm to the base, they show four pins two on each side. If that is them the best way is going to be drilling a small hole through the bottom of the hole that has the broken dowel pins and tap them out with a small punch. I can't tell from the manual but it looks like it should hurt drilling a small hole there but do it at your own risk. You will have to be able to get the drill straight under the hole and I don't know if you can. If there is some thing in the way you could use a 90 degree drill head but then your just buying more stuff to try. You said the pin got driven farther down the hole, if you have enough room to put a shorter in on top of the broken one and have it deep enough to keep the parts from turning. The bolt holds it tight, the pins are just to keep the two parts from twisting. If they are dowel pins you won't be able to drill the pins, they are very hard. Hope this helps.
Scott

Thanks Scott.
Mine is a 28-245 (3/4hp, open stand).
Yes, it's the 2 pins that hold the upper arm to the base.

I may try the drill from behind method. If that's still too tight, I may use the pen torch to get it move a bit.
Thought about how/if I could drill straight, we'll see. May have to further disassemble the saw.

Oh, well.

 

[red f]

Please don't use a cutting torch on this except to heat it. I've done a fair bit of welding and cutting and the risk of trashing your cast iron is way too high. I don't know about heating, but I do know that when welding on cast iron you need to do pre and post heating to control the expansion and contraction of the metal to prevent the cracking of the part.

If at all possible do the drill from below and drive out method.

 

[fsdogwood]

I've studied the arm and base, it turned out that, out of the 4 broken pieces, I might only be able to drill 2 of them from the back side and try to push them
out, so drilling from back won't help.

Now I was thinking about drilling new holes. What I wanted to do is to use the
existing holes in the riser block. Since the holes are diagonal, I wanted to flip
the riser block upside down, so that I can re-use the existing holes in the riser
block, at least I am not messing up with the rise block.

I've put a piece paper on the riser block, with pencil to mark out the holes, and
by stacking the 2 pieces of paper, I have 4 holes in 1 piece of paper.

What I need do now is to glue the paper to the base (or arm), try to align 2 of the the punched holes (in paper) with the broken pins, then drill in the cast marked by
the other holes (may even use hand drill)

Will update any progress here.

 

[fsdogwood]

Just put the riser block on, as is. Tightned the bolt/nut tight enough such that the lock washer is flat, and checked that the upper arm won't move by hand push.
Will try put a blade on and see how it tracks.

Appreciate your help.

 

[DaveD]

Got a welder? Even an Oxy/acetelene one? Take a steel nut with a hole in it that will just fit over the dowel. Put it over the dowel. Hit it with the welder and essentially weld the dowel to the nut. Now you have something to grab on to.

You can weld a bigger nut to the previous nut so you can get a better grip. You can also weld something to the current nuts so you can put a slide hammer on it and then yank it out that way. If the weld between the nut and the dowel doesn't hole just repeat the process until you get it yanked out.

The process of welding a nut on to a broken threaded bolt/stud will also work in those instances where you break a bolt head off. You just need something bigger to put the wrench (impact works better) on.

 

[fsdogwood]

Got a welder? Even an Oxy/acetelene one? Take a steel nut with a hole in it that will just fit over the dowel. Put it over the dowel. Hit it with the welder and essentially weld the dowel to the nut. Now you have something to grab on to.

You can weld a bigger nut to the previous nut so you can get a better grip. You can also weld something to the current nuts so you can put a slide hammer on it and then yank it out that way. If the weld between the nut and the dowel doesn't hole just repeat the process until you get it yanked out.

The process of welding a nut on to a broken threaded bolt/stud will also work in those instances where you break a bolt head off. You just need something bigger to put the wrench (impact works better) on.

Thanks and this sounds a good idea.
As in my last post, I put the saw back on (including the riser), with the broken pins. Even if I am not comfortable with the result.
I'll get some blades, and may get a welder(torch) from the Borg to see if it'll work.

Do have a question though, will the welder work for un-even surface?

Appreciated

 

[DaveD]

The real goal is to get something that is steel with a hole in it that just fits over what you want to weld it to. That limits the weld area to, hopefully, just the stud you want to get out and the 'thing' with the hole. You could use a washer for the initial weld too. Then weld a nut, pull stud, or whatever to the washer.

If what you have is a rough casting that the stud is stuck in then, from a welding standpoint that is even better since the roughness is going to inhibit the weld from sticking to the casting. You don't want to go overboard with the welding. The goal is to just weld the washer/nut to the stud and not slop over to the casting itself.

If you want additional protection, protect the casting with a thin piece of copper sheet. The weld won't stic to the copper.

Good luck.