Line Boring

[psient]

Hi:

I have an air bearing that was damaged in shipment . I may have to line bore a hole in a fabricated collar to replace the damaged piece of casting that fractured.

I was thinking that this was a place to find some good literature or videos, or advice, on the general technique of placing a bore dead center on another bore several inches away.

Thus one side of the casting is intact and the other is fractured with hole that is lined on both sides separated by about 3" of space. I need to bore the side that is damaged exactly opposite the intact side. I figure if I centered the bore through the existing undamaged bore I could make a pretty dead-on corresponding hole.

I don't know if my explanation is clear so I've posted some pictures along with this thread.

Thanks to all,

Jon

 

[Pete Wass]

Just a WAG but

I would be thinking with the way welding has advanced over time someone should be able to restore that tab.

 

[Joel]

I would not recommend welding or brazing on an air bearing. That looks to be an easy repair.

We know you have an air bearing for #2 or a Monoset Tool and cutter grinder. Do you have a Bridgeport type mill, drill press or just hand tools. How I would repair it in my shop may not be an option for you. Are you a T&C shop only or do you have general machining capabilities?

 

[jackie schmidt]

Fix

That appears to be cast iron. For years, (centurys), broken cast iron pieces were fixed by brazing. The trick is, finding someone who can braze worth a darn nowdays.

If some one brought that into my shop, I would braze a new ear on the piece, (not using that broken piece), ring it up on a true mandrel, skin the face dead true, then re-drill and tap the hole.

The secret to brazing cast iron is heat, most do not get the piece hot enough. You darned near have to get it a dull red at the spot to be brazed. When you hit the heat right, it will amaze you how the metal will flow in and take as you hit it with a fluxed up rod.

One advantage of brazing is that it does not induce warpage as much as Ni-Rod or other welding rods designed to weld cast iron. Plus, you can easilly machine the brazed joint.

If done properly, a brazed joint is as strong as the originol piece.......jackie

 

[M.D.Spencer]

How long is that piece?

If you lived a little closer I would take it to work and have Dick weld it.He's the only guy I know that can weld Cast Iron. If the part isn't that long, it could be bored on a Bridgeport. Me, I would set it up on a Small DeVlieg with a Rotary table and do it all there. You can pick up one side and spin it around and bore from the other side and you are dead on.

Why is there a threaded hole to a threaded hole?? What is this part for??

 

[Joel]

“What is this part for??” It’s an air bearing for a tool and cutter grinder. Mostly likely a Cincinnati-Milacron No. 2 or a Monoset. For those that have not seen one in used they are very cool. You have a chromed spindle that is the tool holder. The chromed spindle goes into the part you see. The unit is pressurized with filtered air. The chromed spindle floats on a very thin film of air. You have zero friction for both rotation and in and out. This zero friction extremely smooth movement products a much better surface finishes on the end mill or reamer that you are grinding.

Triple R systems http://www.triplersystems.com purchased Morgan-Denver about ten years ago. They list air bearings http://www.triplersystems.com/Parts_i2398147.html?catId=166875 I have a rebuilt Monoset from them. Excellent machine.

The housing that you have was honed to fit the spindle. When they are new a finger print on the spindle will create significant friction. If you use properly filtered air and never move the spindle unless it is pressured they never wear. That is why I do not recommend brazing. If you braze it and it goes out of round by more than a couple of tenths you will have serious issues. That’s not the end of the world as you can replace the brass races and have them re-honed to match the spindle.

From the pictures it looks like you have a fair amount of wear on the race. Have you pressurized it and checked side moment?



Joel

 

[psient]

Thanks very much to all that responded to my question.

Brazing or welding is not an option IMO. I feel the heat and stress that it creates would have unpredictable results.

I have a tentative solution that avoids heating any metal. However, my original intent was to gain info on line boring. Has anyone ever done this?

Tanks agin,

Jon

 

[psient]

“What is this part for??”

Triple R systems http://www.triplersystems.com purchased Morgan-Denver about ten years ago. They list air bearings http://www.triplersystems.com/Parts_i2398147.html?catId=166875

From the pictures it looks like you have a fair amount of wear on the race. Have you pressurized it and checked side moment?

Joel

Thanks for the heads-up concerning Triple R.

No I haven't pressurized it yet. The cost was $250 so replacing the races and honing them is a possibility after the fracture is fixed.

Have you ever done line boring Joel?

Thanks,

Jon

 

[Pete Wass]

The reason I suggested welding

Thanks for the heads-up concerning Triple R.

No I haven't pressurized it yet. The cost was $250 so replacing the races and honing them is a possibility after the fracture is fixed.

Have you ever done line boring Joel?

Thanks,

Jon

not to cause an uproar but I can't see the oposite side of the item you made pictures of. This was one reason I suggested welding. In another life I worked for a few years in the Machine tool rebuilding business. I have seen a number of castings of unique and hard to make items welded successfully. As Jackie sez, cast iron is stable and he is right, knowing how to braze is all important.

It's been 40 years now since I worked in that industry so I figured time and brought fourth some process to be able to glom cast iron like material on to a surface such as that easily. I guess time doesn't always give the gifts we would like, eh? We old folks use to repair things back in the day; re-sole shoes, patch tires, plug holes in water buckets, re-line brake shoes; those kind of things.

 

[psient]

not to cause an uproar but I can't see the oposite side of the item you made pictures of. We old folks use to repair things back in the day; re-sole shoes, patch tires, plug holes in water buckets, re-line brake shoes; those kind of things.

HI:

Sorry, my bad. I've included pix of the fixture.

I accept the 'WE old folks' as a compliment. I was born in the middle of the 20th century. That makes me what . . . younger but not young yes?



Thanks for the input Pete.

 

[Rustystud]

Fixing cast iron

Brazing is one option and tig welding is another. The heat can be controlled better with the tig process.

http://www.locknstitch.com/CastIronWelding.htm



Nat Lambeth

 

[psient]

Brazing is one option and tig welding is another. The heat can be controlled better with the tig process.

http://www.locknstitch.com/CastIronWelding.htm



Nat Lambeth

Hi Nat:

Thanks. Very interesting site! Did you look at the pix?

Jon

 

[Joel]

Hi Jon

Yes I have line bored many items. The term line bored is nothing more machining the bores on several part ore bores with one spindle location. You would not be line boring this part as you are just locating of the non-damage tapped hole. Line boring is normal done on larger items such as construction equipment field repairs or items that are built on sites that require shafts with bearing like drag line or other larger earth moving equipment.

I looked at some of your old posts and I see that you have a 6X10.5 bandsaw, a Mig welder, a combination welder, an OA cutting rig, a 5hp rotary phase converter, a Bridgeport 1 series 2hp knee mill and a lathe so this repair should be easy.

I am guessing that you want to do some tool grinding and you found a deal on a Morgan Denver Air Bearing Fixture with the Universal Base. Am I correct in assuming that you will build the rest of the machine? What are you using as a grinding head?

The tapped hole that is damaged is for the Rocker arm pivot centers. They are nothing more than pointed set screws. The right angle tapped hole is for the lock screw. When you replace it do not forget to add a brass or lead piece to act as a thread protector. They probability weren’t parallel to the center line when new.

The Rocker arm tilts the fixture away for easy movement from one flute to the next. The location of these tapped holes is not critical. If you are using the spindle of the air bearing as the only movement it does matter if it is off in any direction. That’s what you will be using on the side of end mills, reamers and tap flutes.

The only time it would matters is if you doing taper reamers or taped end mills. These cannot be with an air bearing movement as the air bearing can only cut parallel side. To do tapers you need an additional axis of movement.

If your repair is off .020” you will never notice it.

I have attached some links for simple air bearing T&C grinds that should help you design the rest of the machine.

http://igrind.com/products/nova/AirBearingFixture.htm

http://www.cnccookbook.com/CCBDToolGrinder.htm

http://cuttermasters.com/Products/cuttermaster.html

http://www.ipstool.com/Catalog/0252.pdf

http://www.penntoolco.com/catalog/products/products.cfm?categoryID=5833

http://www.chesteruk.net/store/brierley_cuttermaster_tc2_tool_&_cutter_grinder.htm

http://www.discount-tools.com/catalogs/gen/496.pdf

 

[psient]

Yes I have line bored many items. The term line bored is nothing more machining the bores on several part ore bores with one spindle location.

1. Thanks for the defining paragraph. Are the principles of orienting part and boring tool associated with line boring different in conception from orienting center of bore and optics in 'bore sighting?' I selected this forum due to reasoning the percepts similarities.

I am guessing that you want to do some tool grinding and you found a deal on a Morgan Denver Air Bearing Fixture with the Universal Base.

2. Exactly. In fact the price was very good for what I received. I was less than enthusiastic about the purchase when I opened the packaging and discovered the damage. I guess it goes with the territory.

As to my aspirations for my home shop . . . along with the machines you mention

Right after the air bearing I discovered a K. O. Lee BA960 for 160 bucks rough but definitely serviceable. A few days after I purchased the KO a very nice Foley-Belsaw 380 T&C came along with all attachments and 10 new wheels + the same company's Carbide Tool grinder with attachments and wheels for 150 bucks so I purchased them as well. I also have a tapmatic tap head and a nice hand-tapper. I guess I'm heading for the restoration business.

When you replace it do not forget to add a brass or lead piece to act as a thread protector. They probability weren’t parallel to the center line when new.

3. This is the only confusing bit of info you gave me. Could you please elaborate its meaning for me?

To do tapers you need an additional axis of movement.

4. So you'd have to move in the Y axis simultaneously with the bearing's X axis transit? The KO Lee's table swings to allow for tapers.

If your repair is off .020” you will never notice it.

5. Great then there's no real snag in the repair!!!!

 

[psient]

Joel:

Here's a pix of the K.O. Lee I referred to above.

Thanks very much for all of your feedback!

Jon

 

[Joel]

Hi Jon

1. These sites should answer your questions on line boring.

http://thelineboringbook.com
http://www.youtube.com/watch?v=qfsUY6UVVgI&feature=related
http://www.yorkmachine.com/products-4-14.php
http://www.americanmachinetools.com/line_boring.htm


2. Wow!!!!! you are getting a great shop at awesome prices. I am not familiar with the Foley-Belsaw 380 T&C. Would you post a picture? You stated it came with 10 wheels. If they are diamond only use the diamond for carbide. If you have any CBN only use them for HSS. Diamond and CBN are very expensive and easily damaged if misused. Both diamond and CBN wheel require very light cuts to give good wheel life. I normally only take .0002 max. per cut with my diamond and CBN wheels. Silicon Carbide Grinding Wheels for carbide are cheap and you can push them much harder but the break down (wear) fast. This makes it hard to get accurate sizes on your tools. This is the same for Aluminum Oxide wheels for HSS.

3. Sorry to confuse you. Too simplify let’s talk about grinding a straight fluted chucking reamer with the air bearing mounted on the K.O. Lee. After you indicate the reamer in and have set your grinding wheel height and angle on the K.O. Lee you simply touch off on the reamer with your grinding wheel using the X axis of the K.O. Lee. To make the cut on the reamer push the spindle of the air bearing. This will be the Y axis moment. As you see the movement is in a straight line so all your cuts will be parallel with each other. Now if you had a straight fluted taper pin reamer is this setup how would you make the cut using the spindle of the air bearing? Simple answer is you cannot make this cut with the spindle movement of the air bearing.

4. With the tools you have you a have at least two options to cut tapers. First you can use your air bearing universal base to set the taper. In this option the air bearing is used to index only. The Y axis movement is the table of the K.O. Lee and NOT the spindle of the air bearing. For the second option don’t use the air bearing. Use the universal table adjustment of the K.O. Lee to set the angle of the taper. Mount the taper pin reamer between centers (or if you have the K.O. Lee work holding head you can use that also). Again the Y-axis movement is provided by the table of the K.O. Lee.

Hope this helps

Joel

 

[psient]

Boyar Schultz surface grinder

Joel:

Do you have any opinion about a Boyar and Schultz surface grinder (6/12). I can pick one up for $150 bucks . . . I think. Have to run out and look at it but it's certainly cheap enough.

The only criticism I can find is that the x axis travels via rack and pinion. Many prefer cable.

How spot-on does a grinder have to be in order to be serviceable? I mean I wouldn't be making test bars but I could easily see my self resurfacing the K. O. Lee's table with it.

I would then . . . of course start to learn hand-scraping.

Jon

 

[Joel]

Jon

I have no opinion about a Boyar and Schultz surface grinder. I have only used or worked on larger hydraulic grinders.

Joel

 

[AMMASHOOTA]

That appears to be cast iron. For years, (centurys), broken cast iron pieces were fixed by brazing. The trick is, finding someone who can braze worth a darn nowdays.

If some one brought that into my shop, I would braze a new ear on the piece, (not using that broken piece), ring it up on a true mandrel, skin the face dead true, then re-drill and tap the hole.

The secret to brazing cast iron is heat, most do not get the piece hot enough. You darned near have to get it a dull red at the spot to be brazed. When you hit the heat right, it will amaze you how the metal will flow in and take as you hit it with a fluxed up rod.

One advantage of brazing is that it does not induce warpage as much as Ni-Rod or other welding rods designed to weld cast iron. Plus, you can easilly machine the brazed joint.

If done properly, a brazed joint is as strong as the originol piece.......jackie

i'm glad i finally found someone else who understands the benefits of brazing.

i build quite a few custom handguns, and invariabley i will need to build up material on trigger bars (striker fired pistols) and i do it by brazing.

we are only talking about maybe adding 30 thou after reshaping, but the whole process is relatively straightforward with no warpage to the small parts.