Removing a boring-head arbor

[jwmelvin]

I bought a Criterion boring head on eBay. The head seems to be in nice condition but the arbor is a little rough. I bought an R8 replacement and would like to swap it with the straight one currently on the head. But my first attempt wasn’t a success. I held the head in a vise with some wood blocks and tried to grab the shoulder of the arbor with a pipe wrench. I was trying to avoid damaging the arbor shaft itself. No success.

I can use some penetrating oil but are there any other approaches that may help? I figured heat would be risky to the head. It’s not easy to grab onto the arbor without going for its main shaft.

Such a basic question; I feel like I’m back years ago looking at my first rusty, stuck suspension bolt. But a sawzall and angle grinder don’t seem like the best approach...

Oh, here’s a picture of the patient:

 

[Lo-Fi]

If the straight arbor is rough and being replaced anyway, you want to go for holding that tightly in a vise and not worry too much about it. You could even grind a couple of small flats at the top end. The boring head itself is easy, just pop a couple of pins/tools in the holes and use a wrench over both of them right up next to the face. It'll seem a bit brutal, but it's much kinder to it than trying to grip the head on the vise!

If the PO locktited the arbor in, you're probably onto a no hope without a bit of gentle heat though. It won't do the boring head any harm as long as you don't go crazy. Doesn't need much; only warm enough so it's just uncomfortable to touch should do the trick.

 

[Martin W]

Try here

Problem removing arbor on Criterion boring head

I just bought a used Criterion 203 boring head for the 949TS. It came with a 1 in straight shank, but I can't use it, so bought a Criterion R8 1 1/2-18 shank. Problem I can't seem to be able to undo the 1 in shank. Tried to hold the shank tight in lathe chuck and using moderate force on an...

www.hobby-machinist.com

 

[jwmelvin]

Try here

Thank you... will try.

 

[jwmelvin]

ugh. Nothing has worked so far. I ground a couple flats on the arbor to hold it in a vise, and also tried holding it in the lathe 3-jaw, while smacking a bar held transverse in the boring head. I heated the thread area too.

 

[Nutfarmer]

Heat the boring head up with a heat gun not a torch to a max of 400 degrees. This won't effect the temper of the head and may expand it enough to allow removal. Care is required not to over do it.

 

[kd4gij]

Did you take the head apart and see if there is a screw in the middle?

 

[Z2V]

Take a look here, this might work for you

Alternate Method For Removing Stubborn Drill Chuck Arbors

I thought we had a tips & tricks section but I guess not so here it goes. We all know wedges are the most common way for removing drill chuck arbors. But they aren't always successful & for certain arbor sizes they won't work at all. Other solutions are to make your own for sizes not covered...

www.hobby-machinist.com

 

[BtoVin83]

From boring they get stuck on pretty tight. Mine's stuck and when I get around to replacing it I will cut it off an bore it out in the lathe, better than putting wrench marks on the head.

 

[mikey]

The arbor is threaded into the back of the boring head with a 7/8-20 RH thread. My suggestion is to make a simple aluminum fixture plate by boring a hole the OD of the head, then cut a slot from the outer edge of the plate into the hole. Slip the head in the hole and clamp the plate in the vise so it closes the slot and traps the head. Then turn the arbor off using the flats you created already.