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View Full Version : Wow, cool boring bar!!



tmc_31
12-07-2013, 12:07 AM
I have had a project laying on the shelf for a few months for want of a decent boring bar. I needed to enlarge a 1-1/4" X 6" hole to 1-1/2" in a 2-1/2" A36 bar. I tried a homemade 3/4" bar with a HSS bit. Way too much flex boring that deep. Then I tried a brazed carbide bar that came with a boring set I got for Christmas a few years ago. It was not long enough to bore through the part so I was I was going to have to bore from on end then turn it around to get the other end.

I decided to wait on the project until I could find a better bar. My first thought was a 3/4"X10" solid carbide index-able bar, until I found out how much they cost.

Last week I ran across an ad on Craigslist from a guy who was selling about 70 or so used boring bars. I called him and said he had a 1"X12" Iscar steel index -able bar with new looking tpg insert in it. So I bit.

All I can say is WOW!! There was no discernible flex in the bar and the finish was marvelous.

At $60 including shipping, it doesn't qualify as a tool gloat but I am sure happy with the results.

Tim

JRouche
12-07-2013, 01:50 AM
Right! A36 (structural steel) machines great when you are past the scale. Good metal fpr the project. JR

Jaakko Fagerlund
12-07-2013, 02:29 AM
Good it worked out and you found a nice new tool :) Boring is always a little PITA to get all the parameters correct, but it helps to play more with them. I usually tend to raise the boring bar somewhat above center line if I have a very deep hole, so that if or actually when the boring bar flexes, it doesn't dig in to the material and start self destruction sequence. If it tries to keep sounds like a squeeling pig, just lower the surface speed and/or change feed rate a little.

Also the cutting tool geometry plays a huge role, the carbide insert you used might have been more easily cutting than the HSS and the brazed carbide. For that small holes or very fine finishes one wants an insert that is designed for finishing operations and has very little nose radius, so that all the forces are as small as possible.

boslab
12-07-2013, 03:50 AM
I get the dreaded chatter with mine too, unfortunatly my toolpost can only manage about 3/4" square, i think that i ought to make a toolpost just for boring but everytime i think about it i seem to get a brainfart!, last thing i bored i used a horizontal mill with the biggest bar i had bolted to the table and the work held on a faceplate on the spindle, would have been great but for the fact i screwed up and bored it oversize! Typical
Mark

vpt
12-07-2013, 08:51 AM
When room allows I step up from my 1/2" cummins valves ground into boring bars to big Bert, Bert is a 3/4x 1.75" HSS bar.

http://img802.imageshack.us/img802/8214/hydraulicram012.jpg

tmc_31
12-07-2013, 01:42 PM
Thanks guys:) Andy I'd like to see a picture of your boring bars made out of Cummins valves. Big Bert looks plenty stout. Yep boring has always been a PITA for me too. Maybe because I don't do it very often.

Tim

vpt
12-07-2013, 03:55 PM
It is a pita. Not only dealing with deflection but chip build up and even seeing what you are doing. Thats why I try to use the biggest bar possible so less stuff seems to effect the work.

I have posted my cummins valves a few times. They aren't super great but they work and I have a bunch of them. lol

You can see the rings for the cap retainers, the near end was the valve face side (hard side) that I ground down to what I figured would be a useful cutting edge. I have made another for a special operation just this last summer I believe.

http://img254.imageshack.us/img254/9068/boringbar015.jpg

This is the special one I made to make an internal o-ring groove.
http://img138.imageshack.us/img138/4440/excursioncargo013.jpg

http://img824.imageshack.us/img824/6674/hydraulicram008.jpg

tmc_31
12-07-2013, 11:26 PM
Thanks for posting those Andy. That is a great way to recycle those valves. I never would have thought of doing that.

Tim

PStechPaul
12-08-2013, 01:07 AM
Not having experience with boring, I jammed the MT2 base of the boring bar holder in the tailstock of my lathe, and adjusted the radius a few thousandths at a time using the dial. It worked pretty well, perhaps because this was just an Oilite bearing that needed to be enlarged from 1.125 to 1.250 inches ID:

http://enginuitysystems.com/pix/Lathe_Boring_0590_800x600.png

http://enginuitysystems.com/pix/Lathe_Boring_0592_800x600.png

TGTool
12-08-2013, 04:33 PM
Not having experience with boring, I jammed the MT2 base of the boring bar holder in the tailstock of my lathe, and adjusted the radius a few thousandths at a time using the dial. It worked pretty well, perhaps because this was just an Oilite bearing that needed to be enlarged from 1.125 to 1.250 inches ID:

http://enginuitysystems.com/pix/Lathe_Boring_0590_800x600.png



Too funny! My immediate thought looking at the photo was, "He's got the orientation wrong and cutting in the wrong place!" Then just a moment later it struck me that it doesn't make any difference. The tailstock doesn't move in any direction, only the boring bar advance. Thanks for a private chuckle. :)

Black_Moons
12-10-2013, 07:14 AM
Actually, it does look like that boring bar is backwards and he was cutting with the steel backside of it and not the brazed carbide part...

EVguru
12-10-2013, 09:19 AM
One trick is to replace the top-slide/compound with a dedicated boring bar holder for maximum rigidity.

I once had to bore something on a badly worn out Myford and to stop chatter had a lead weigh on the end of a V belt hooked over the toolpost.

tmc_31
12-10-2013, 12:00 PM
Paul,

I broke my compound a couple of years ago doing something stupid. I have since repaired it. But while I was waiting for the parts I built a solid block to sit on top of the cross slide. I mounted my CA QCTP to that (thanks for the tip Sir John). That has markedly improved the rigidity of my lathe for most operations I do on the lathe. Now I leave the compound in the drawer unless I am threading or turning a taper. Also it turns out that the boring bar holder that came with my QCTP set is just a fit for the 1" Iscar boring bar when you remove the split center sleeve. This makes for a much more rigid set up.

Tim

tmc_31
12-10-2013, 12:15 PM
Paul,

I must admit that I didn't understand why you were using your boring tool in that manner instead of using a normal tool holder and boring bar. I am still not sure, but it apparently works just fine.

One of the operations that I am going to have to do on this project is cut an internal o-ring groove inside a 1" hole. It has occurred to me that using your method with the boring head along with Andy's Cummins valve grooving tool, I will be able to actually see the tool engaging the inside of the bore. If I can actually see what is going on I think it will be easier for me to cut the groove as opposed to using a conventional boring tool holder and only seeing the groove after it has been cut.

Thanks guys

Tim

vpt
12-10-2013, 12:36 PM
Paul,

I must admit that I didn't understand why you were using your boring tool in that manner instead of using a normal tool holder and boring bar. I am still not sure, but it apparently works just fine.

One of the operations that I am going to have to do on this project is cut an internal o-ring groove inside a 1" hole. It has occurred to me that using your method with the boring head along with Andy's Cummins valve grooving tool, I will be able to actually see the tool engaging the inside of the bore. If I can actually see what is going on I think it will be easier for me to cut the groove as opposed to using a conventional boring tool holder and only seeing the groove after it has been cut.

Thanks guys

Tim


Thats what I had to do was an internal o-ring groove but in a 2" hole so I could see a little bit of what I was doing. The groove came out perfect but I was a bit nervous doing it because it was my last operation on the part that I already had a day into.

http://img849.imageshack.us/img849/5379/hydraulicram018.jpg

http://img713.imageshack.us/img713/4528/excursioncargo015.jpg

tmc_31
12-10-2013, 12:50 PM
Hey Andy, I've got an '06 D3500. Is that gonna be the same valve?:p

Tim

vpt
12-10-2013, 12:59 PM
Hey Andy, I've got an '06 D3500. Is that gonna be the same valve?:p

Tim

I honestly have no idea what the valves are out of. I just know they say cummins on them and I got them from my father in law who got them from his father who was a semi tractor mechanic. The shaft of the valves is .500"

sawlog
12-10-2013, 01:09 PM
I dont bore that much at home, but when I do I just ue a standard indexable boring bar in the lathe.. What I did was to make sleeves for my boring bars to mount in the quick chang boring bar holdr blocks.. This works just like th boring bar system on CNC lathes and woeks verry well.. You just have to remember to follow the over hang rules of thumb for the boring bar overhang.

PStechPaul
12-10-2013, 03:04 PM
My boring bars have probably 1/4" round shanks that fit into the boring tool holder as shown. It has an assortment of shanks which are round or tapered. The MT2 fits perfectly in the tailstock, so that's why I tried it that way. My toolholder is a quick change turret type that can clamp up to 1/2" or maybe 3/4", but it won't hold the round shanks securely. Perhaps I need to get (or make) a holder with a square shank and a hole with set screws for the boring bar. That might be a good project. It would certainly be easier to use the compound so as to be able to adjust the length and depth of the cut more easily, and it should also be more secure.

I'll have to look at some "normal" boring tool holders to see how this is usually done. :)

Here is my boring bar set (from HF):
http://enginuitysystems.com/pix/Lathe_Boring_Tools_0593_800x600.png

And here is a set of carbide tipped boring bars I bought some time ago. The tips are dipped in a protective plastic material - the actual tools are in good shape. There is probably some surface rust on the shanks, as there is on almost everything I own. That's the price of having a machine shop in a "cave".

http://enginuitysystems.com/pix/Lathe_Boring_Tools_0594_800x600.png

Is this what I should get/make?
http://www.use-enco.com/1/1/16906-steel-boring-bars-377-2055.html

http://www.use-enco.com/ProductImages/0319150I-21.jpg

So, what type of steel should I use for this toolholder, if I decide to make it? I have a 3/4" square 1215 and 1045.

RussZHC
12-10-2013, 04:48 PM
Perhaps I need to get (or make) a holder with a square shank and a hole with set screws for the boring bar. That might be a good project. It would certainly be easier to use the compound so as to be able to adjust the length and depth of the cut more easily, and it should also be more secure.

You could also go the "mirror" of that, get rid of the turret style holder for boring ops, put a great lump in its place and bore a round hole to hold the boring bars (split it on that side, a couple of SHCS). One of the things I have found with boring is the fewer connections the better. I too still need to follow John S. advice and get rid of the compound for most day to day use.

If you were using a typical quick change tool post, you could also get a holder that is meant specifically for either boring bars, or one that has a Morse taper so you could use the boring head as is...there is really no reason I can see that something similar could not be fitted to what you have. Having a way to quickly mount Morse taper tooling in both tailstock and to the cross slide/compound can be quite handy.

tmc_31
12-10-2013, 06:11 PM
Paul,

If you have a standard 4 way tool post like what comes with most hobby sized lathes these days or a quick change "aloris" style tool post, that Enco boring bar should be fine. I have some of those same type boring bars that came with my boring head set (very similar to yours). I tried to use them in a standard tool block (holder) with my Aloris style tool post. I did not have much success. Maybe a holder like that would grip it better and make it more rigid.

That Enco boring bar and holder set is sure pretty inexpensive. Hard to tell from the picture but it looks like the holder has a slit down one side. It would need to in order to grip the boring bar well. I looked at their (Enco's) selection and they don't seem to have one that will fit a 1/4" shank boring bar. So, you may have to make one. It doesn't look like it would be hard to do. I would think a mild steel like 1018 or A36 (the A36 will provide a nicer finish) would do fine. If you had it and wanted to make something really nice, you could use 4140 and then harden it.

Tim

tmc_31
12-10-2013, 06:27 PM
Andy, are you just grinding the valve into the shape you want or are you brazing a carbide tip on it?

I am searching for what material they are made from. My guess is that the valve body is solid (not sodium filled) right?

Thanks,

Tim

vpt
12-10-2013, 06:51 PM
Andy, are you just grinding the valve into the shape you want or are you brazing a carbide tip on it?

I am searching for what material they are made from. My guess is that the valve body is solid (not sodium filled) right?

Thanks,

Tim



Yes just grinding whatever cut edge I need into the valve face part. From what I understand (heard) the sodium filled ones aren't common, and were mostly in performance type engines. You DON'T want sodium filled valves.

J. Randall
12-12-2013, 01:03 AM
I was just going to caution you on using valves because some of them are sodium filled. I don't know which ones, but I think there are some modern diesels using them, just be sure you know for sure before making tooling from one.
James