Babbitt boring bar RPM?

[Mark Gregush]

What would a good target RPM for the boring bar for doing the babbit mains with say a feed rate of around 36 thread per inch be?

I have a hydraulic pump/motor/tank that came off a Westinghouse X-ray machine so am thinking about a direct drive fluid motor setup.

Next question would be: Any suggestions for a fluid motor that would be in the asked for RPM range? Any motor I get is going to have to be something used and lower cost. Looking online, kinda hit the wall because I really don't know that field and what information I have found is not real helpful re motor speed range as I am trying to stay away from gear or pulley speed reduction.

[Kerry]

My line boring bar, I run at 350 RPM with finger pressure for feeding the tool bar and my rod boring bar runs at 400 RPM, as for TPI the self feed on my rod machine is that fine, like a phonograph cylinder, I couldn't count per inch.

[Dan Hatch]

Save yourself some work and look around for a Torbin Arp drive. Mate it to a Cene French boring frame and you are off to the races.. Torbin Arp stuff like a TA 14 we’re top of line but now days no one wants them. Dan

[Dan McEachern]

About 350-400 RPM is a good speed to shoot for. Your 36 TPI is way too coarse for a finish cut- thats about .027"/revolution and you need something in the range of .002/.003"/rev for an acceptable finish. Dan's suggestion to find a Tobin-Arp drive unit is a good one. I may have an extra one laying around if someone is interested. They incorporate a small hydraulic pump and a needle valve driving a pair of hydraulic cylinders for the feed mechanism, so they are almost infinitely adjustable and very smooth.

[Joe Bell]

Mine is a variable speed so I hog it out on first couple passes then slow the feed down to give mirror finish.

[got10carz]

I bore at 400 RPM. Lots of feed choices.

[Mark Gregush]

I have the KR Wilson boaring bar frame and bar so just need a way to feed it. The boring bar now has adjustable cutters.
I thought about making a feed using the carriage on my 10" Atlas and a keyed sliding shaft that I have, but don't want to just set the block on the rails which has the 54" rails with the tail stock end is in a tight corner. The rails are not really that strong so would have to bridge them and where the lathe is sitting, I would have to build a crane to lift the block up and there is no room to do that, I don't want to end up on my back for a week.
I have a nasty KRW ream that might work for final cut, but don't want to have it ground for just a single job, being of the only grind to clean-up school.
The feed rate is not set in stone as I would have to make the feed shaft and nut so could go finer then 36. The Tobin-Arp drive (been kinda looking for one or something similar but of the thread feed type) and Gene French suggestions are good, but frankly, too far outside my budget even if I did resell after using this one time.
The idea of adapting and using a fluid drive motor was inspired after watching some You-Tube videos of the portable units in action and trying to use what I have on hand with only buying minimal extras that I don't have such as a used drive motor and some steel.
Thanks for the target RPM range, that really helps.
Mark

[Gene_French]

Mark:
i did not see any indication of how you were going to achieve a feed movement in addition to the rotation of the boring bar ... a 36 pitch screw is way too course a feed ... you would be able to reduce the feed action by a simple belt drive reduction ... i will assume that the 2 movements are seperate ... that being the boring bar rotation is a separate action from the feed movement ... if this is the case a reduction of 10:1 would still give a feed rate of .0027 per rev. ... a hydraulic feed or a servo motor or stepper motor drive is also a good possibility ...you may also consider the tool bit design and a hand feed operation ... my bits are of a "LEFT HAND LEAD / RIGHT HAND CUT " design ... this allows for a controllable hand feed , since the bit does not "spiral " into the work ...i hope this helps , we sometimes over think a question ... the simple is often difficult to see ... MERRY CHRISTMAS all ...Gene French

[Dan Hatch]

Before I got my TA14 I was working on using a brake drum lathe to turn and feed a boring bar. They are adjustable feed and speed. You could find them reasonable.
Torbin Arps units work great so I gave up on that idea.

[Gene_French]

Mark:
a very simple solution is a simple drill press ... use the spindle for rotation and the quill feed for your feed movement ... you will also have the quill stop to help with the thrust facing operations...Merry Christmas ...Gene French

[Mark Gregush]

Thank you everyone. Back to the drawing board. I was basing my feed rate on the KR Wilson combination machine and now can see that isn't going to work out the way I was planning.
Merry Christmas and a Happy New Year!
Mark

[Dan Hatch]

The KRW machines are designed to use the reamer. They do a good job with that. But undersized reamers are few. I had a local guy that ground mine but he closed. Hard to find a grinder that with take that long a reamer. Last ones he did for me were $400 each.

[Mark Gregush]

The KRW machines are designed to use the reamer. They do a good job with that. But undersized reamers are few. I had a local guy that ground mine but he closed. Hard to find a grinder that with take that long a reamer. Last ones he did for me were $400 each.

Thanks Dan. That is why I don't want to mess around with having one ground for one time use. If I had the crank ground to one of the standard undersizes, that might be different. Even then I would have to think long and hard before putting down the cash to do so, not enough call around here to recoup the cost. Then of course, it wouldn't be the needed size later.

[BRENT in 10-uh-C]

The KRW machines are designed to use the reamer. They do a good job with that. But undersized reamers are few. I had a local guy that ground mine but he closed. Hard to find a grinder that with take that long a reamer. Last ones he did for me were $400 each.

Not trying to hi-jack Mark's thread but I know that cylindrical grinders are all but obsolete these days but has anyone ever used a crank grinder to sharpen a reamer? My grinder is set-up strictly for plunge grinding, but I suspect I could sweep once I had the bulk removed. Not sure how my Arnold gage would work on a reamer ...and maybe that is the issue??



Mark, something that Dan and I have spoken about over the years is most KR Wilson Frames have the bushings worn just enough where they cannot hold/support the bar tight enough without creating some harmonics. Dan & I discussed using a sacrificial T engine block as a boring bar frame where we would bore the block's mains large enough that it would hold a 0.750" ID bushing in all 3 mains. Then after making a 0.750" boring bar, the bearings in the KRW Frame could be bored out to accept new bushings, ...and then those new Frame bushings align-bored to accept your Model-T boring bar. I think our consensus has been that when you added all the time you will spend modifying an old KRW Frame to be good as new, you could spend that same amount of time (-or likely less!!) working part-time at McDonalds to earn the money to buy one of Gene's frames and be done with it.

While I use a TA14 to line-bore most projects in my shop, I do own several Tobin Arp SB bearing resizers. I have strongly considered using one of those as a drive-unit for powering one of Gene's frames and boring bars. The Tobin Arp drive motors they used on many of their tools are really very nice and produce a beautiful finish because of their hydraulic feed and infinite speeds. These units also use variable pulleys to control the bar rotational surface feet per minute speeds. If you are looking for a drive unit, I would suggest looking for a TA drive motor and adapt that.

[Jack Putnam, in Ohio]

KRW did supply an optional hand crank attachment for hand boring and reaming newly poured bearings.
If you had the boring frame and reamers but did not spend the beg bucks to buy the combination machine you could do the bearings by hand crank power. The boring bar has a threaded holed in the end for the 40 tpi attachment. I have done it this way ONCE to see if it was possible. it will work but hard on the arm. RPM depended on the operator.

[TrentB]

An alternative is to use a Bridgeport style milling machine equipped with a right angle or horizontal adapter and power feed on the X axis. I have seen this used to power a Wilson line boring jig. With an rpm of about 400 and a very slow table feed this set up bored main bearings to a sufficiently fine finish that a main bearing reamer was not needed.

The feed on a Wilson combination machine is set at 35 threads per inch, or 0.02857. This is way too course for a good finish on main bearings. The Wilson boring bar cuts the bearings to a diameter of 1.242-1.243. Then the bearings were reamed to the final size of 1.250 with the special main bearing reamer. The cutters on the Wilson boring bars were set at the factory and not adjustable. The reamers finished bearings to only one standard size. If a crankshaft’s bearings were worn out of round or undersize, you were suppose to replace it with a new one from Ford.

Mechanics who rebabbitted bearings over the past 70 years using the Wilson machines converted the boring bars to accept adjustable cutters, and had several reamers reground to standard undersizes. The One I knew (and from whom I learned how to do it) had 7 reamers. One was standard, the other six were .005, .010, .015, .020, .025 and .030. Unfortunately, those engine rebuilders are dying off quickly, and few people are stepping up to replace them.

Respectfully Submitted,

Trent Boggess

[Dan Hatch]

I have found that KRW main bearing reamer are not ground square with the world. They have a slight taper to them. The pilots between the reamers are square. That is why the whole reamer must be ground the entire length. Hard to find a grinder that can do the job. I have only found one guy local that could and he has closed his shop years ago.
Using a SB works good to drive a boring bar. Just have to make a brace to keep the frame from moving. Good luck and Merry Christmas.

[David Greenlees]

Mark, 40 years ago, before buying a Tobin Arp line boring machine, I purchased a WWII-era AMMCO Model 42 portable line boring machine seen in the second photo. The feed unit for it is just like the two in the 1st photo and is powered by an electric drill. The feed unit is not what you are looking for but are inexpensive and feed gearboxes have forward and reverse and both rough and fine feel settings and work well for main and cam bearings.

Kwik-Way portable line boring machines also use a similar drive unit. See https://www.fordgarage.com/pages/kwikwa ... ctions.htm

The 2nd photo shows the feed unit on the end of the boring bar set up on the bottom a supercharged 1930 SSK Mercedes block.

You can see several photos of the complete rig @ https://www.publicsurplus.com/sms/aucti ... uc=1606930

The drive end of the shaft slips into a concentric bore on the inside of the boring bar, and the rack and pinion drive with a ball on the end is fastened by a universal adaptor to the engine block.

These line-boring machines are obsolete but can still do excellent work in the hands of a patient operator. You should be able to buy a complete setup from a reasonable seller for about $250 - 500 and sell the rest of the parts not needed or possibly find just a feed unit for less. If my memory serves me right, the boring bar is about 1-1/4" and too large for standard T-sized bearings, but it could be adapted to use a smaller bar.

[Ron Patterson]

In the foreground of this photo you can see the self contained Tobin Arps hydraulic (rotational and horizontal) feed works that can easily be adapted to any Model T align boring fixture.
The beauty of this unit is that they are reasonably easy to find, not terribly expensive, the horizontal feed rate is infinitely adjustable in both directions, the hydraulic feed pump is powered by the rotational action and you can still buy TA repair parts for repairs.

Ron Patterson

[David Greenlees]

In the foreground of this photo you can see the self contained Tobin Arps hydraulic (rotational and horizontal) feed works that can easily be adapted to any Model T align boring fixture.
Ron Patterson

If anyone would like to see how I use a Torbin-Arp machines to line-bore early non-Ford engines and make new bearings check the following links:

https://theoldmotor.com/?p=149961

https://theoldmotor.com/?p=47859

https://theoldmotor.com/?p=56711

These Tobin arp feed units are all used on their connecting rod machines (above) learn more @ https://theoldmotor.com/?p=51174

[Mark Gregush]

Guess I could somehow use these parts to drive the boring bar:

[Mark Gregush]

One more photo. This is where my sliding drive I was going to use on the lathe is coming from. The drive fluid which looks like a master brake cylinder with the reservoir on top. The actual drive is a grooved piece in the housing that is fed by the reservoir and turned by the pulley/sliding shaft at the other end.
The AAMCO unit, I have thought about. The boring bar and boring bar rod/holders would have to be modified or replaced as the smallest size supplied in the kit that I have seen, would be too big for the Model T. I did come across one of the holders on eBay that was made for the smaller Model T boring bar.