nuther BP head bolt question

A J-head is held on by 4 1/2" bolts, as many of us know very well. I am planning to work on my extra J-head, which is at the moment braced up on a rolling platform. J-heads are devilish awkward things to move, lift, or do anything with until they're properly mounted. But I have to work on this one, so I'm planning to mount it on an inexpensive engine stand, procured today for $25. First woops is it won't mount on the 4 fingers of the engine stand, they don't go that close together. So I'm going to make another mount plate, my engine stand mount plate just uses regular 1½" pipe.

I'm wondering if any of you guys know the bolt pattern of these 4 bolts. I stuck a piece of steel under there and punched it using my transfer punches (there are those ubiquitous transfer punches again) but the pattern is really crooked and I figure someone knows the actual designed values. Anyone?

GWE

Reply to
Grant Erwin
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Don't know the values, but you might consider buying a square bracket from an old tracer head, they usually bring about $25 on ebay.

Reply to
ATP*

Reply to
David Billington

I have the BP manual. You are correct, there is a bolt pattern which I never noticed before because it is so small and sort of smudged. Even with 4X magnification I can't really satisfactorily read it. If you don't mind, would you confirm these?

All 4 holes are spaced 1-7/8" vertically from the center of rotation. The upper two holes are spaced 2-11/16" horizontally from the center. The lower two holes are spaced 2.218" horizontally from the center.

Thanks!

GWE

David Bill> The hole position details are in the BP manual I have. If you want I can

Reply to
Grant Erwin

If no one has the answer..Ill go measure the spare 1J head I have in storage.

Anyone need a 1J head, no idea of whats wrong with it..looks to be all there. Has a 1hp pancake motor on it...IRRC.

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner

Reply to
Gunner

OK, after rechecking, it appears I was wrong, I'm mixing up the J and 2J bolt pattern. Here's what I now believe is correct:

The top 2 are spaced 1-7/8" vertically and 2-11/32" horizontally from center. The lower 2 are spaced 2.019" vertically and 2.218" horizontally from center.

GWE

Grant Erw> I have the BP manual. You are correct, there is a bolt pattern which I

Reply to
Grant Erwin

From my diagram the upper 2 holes are spaced 1 7/8" vertically above the centre. The lower 2 holes are spaced 2.019" vertically below the centre.

The upper 2 holes are 2 11/32" horizontally from the centre, although the left dimension lines are not clearly related to the hole in question.

The lower 2 holes horizontal spacing is as you give 2.218"

The numbers are quite clear in my manual.

The holes size is given as 17/32"

H> I have the BP manual. You are correct, there is a bolt pattern which I

Reply to
David Billington

Reply to
David Billington

Well, here's what I *know*. I drilled the bolt pattern to the second set of dimensions I posted and the plate fit perfectly. I drilled 1/2" holes. And in my manual (M-105K, the last and most recent Bridgeport manual) the hole patterns appear different for the J and 2J heads. Anyway, 'nuff said, I made the part, it fits, it's square and tight and right so thanks! - GWE (dimensions repeated:)

The t> From my manual the J head and 2J2 head seem to have the same bolt

Reply to
Grant Erwin

"Gunner" wrote > Anyone need a 1J head, no idea of whats wrong with it..looks to be all

I'm desperateley seeking vertical capability at a bargain price. Can an adapter be made to hang that head on a Hardinge TM-UM? How many sheckles to purchase? Tom Remove pyrotechnics to reply by email.

>
Reply to
Tom Wait

Tom, where are you located? I'm working on my spare Jhead because I want to convert it back to a 1760 motor and see if I like it better than the rebuilt one I'm using now (the older ones were better in some ways) but whichever one I choose, the other one will be available soon in Western Washington State.

It used to be possible to ship a J-head via that place that only goes airport to airport, I got it shipped out here from Pennsylvania for $200. Heavy buggers. But I think that air freight company (was it something express?) raised their rates gigantically so it may be a shocker to ship it.

Anyway, you are likely closer to Gunner (Taft, California) than me (Seattle).

Grant To email me, do NOT 'reply-to', rather visit http://www.t> "Gunner" wrote > Anyone need a 1J head, no

Reply to
Grant Erwin

There may be different ways of measuring the bolt centers, but as far as I can tell, the main head casting is the SAME for both 1J and 2J heads.

Jon

Reply to
Jon Elson

You'd better consider the weight. Even a 1J head is plenty heavy. I don't know how big a Hardinge TM-UM is. But, a complete 1J must weigh close to 200 Lbs. The main casting with the quill in it has got to weigh 100 Lbs, then there's the belt housing and motor. The quill has about 5" travel, so you need to consider the optimum height to mount the head so you can do small work fixtured on the table as well as larger work in a vise. Depending on how much knee (or whatever design the machine uses for Z table travel) movement you have, it could become a limitation.

Taking this big head on and off the machine to convert from vertical to horizontal will require major disassembly or a shop crane. I can just barely lift the motor myself, due to the height over the floor. Handling the main casting with the quill still in it is at the absolute limit of my upper body strength. With oil and swarf all over it, it gets to be a real challenge. This is compared to a 90 Lb 6" milling vise, which I whip up on the table with just a little "oomf" sound.

Jon

Reply to
Jon Elson

"Grant Erwin" wrote

I'm in southeastern Wisconsin, that place known to the rest of the world as the frozen north. Think beer, cheese and Harleys. Tom

Reply to
Tom Wait

A Bridgeport M head is a common addition to a Hardinge TM. In fact theres one up for auction on Ebay all set to go on a Hardinge mill, but I'm afraid the bids will go to the moon. Someone lucky SOB just won a Hardinge mill with an M head on it for $310. It was in NY, to much frieght for my blood. That's why I was curious about Gunners J head. I'm not savvy about the various head designs Bridgeport offers. Just looking for information, and a bargain. Tom

Reply to
Tom Wait

The M head is MUCH lighter! 1/2 Hp, higher speeds, but no lower speed. The M does not have a back gear or a power quill feed. The J head has both, as well as a VERY much larger quill and spindle. The M is available with Bridgeport C taper, MT3 and B&S #7. That limits you to

1/2" tooling, and not a lot of other special arbors are available, like flycutters, boring heads, end mill holders, etc. for these tapers. You can get almost anything ever invented in the R-8 taper.

If the M head is just about "right" for the Hardinge TM, I think you'd find the J head to be too large in some dimension. The distance from the mounting flange area to the bottom of the quill, and to the quill centerline are both several inches larger on the J head. And the weight increase must be 2-3x, also.

On the other hand, on a machine which CAN handle the weight and size differences, the J is a much more versatile head. I changed my round-ram Bridgeport from M to 1J, and have been VERY happy with the upgrade. The tooling advantage I mention above is part of it, but the performance of a boring head, and the ability to run at much slower speeds is also a plus. The slow speed is great when boring, using jeweler's slitting saws and flycutters. I could never get a boring head to work with the M head, without massive chatter marks. I had to grind down a boring head arbor's 3/4" straight shank to 1/2" to fit the M head, which may have been part of the problem. I replaced the shank with an R-8 one when I got the J head, and had no more chatter trouble.

Jon

Reply to
Jon Elson

Grant, could you explain this? Why would the pattern from the actual transfer punch marks be crooked? I mean, the holes are exactly where they are, are they not? So how can the design specs be more accurate than what you're physically measuring?

- Michael

Reply to
DeepDiver

Yes, I can explain this. I wanted to transfer the dimensions to a 6x6x1/4" piece of plate steel, and I wanted them centered and square. The head was not in a position amenable to one guy working on it, to say the least. I was able to lift up the front of it and slip the plate in behind it and set it back down trapping the plate. Then I discovered that my 1/2" transfer punch didn't quite fit into the holes, so I used the 31/64" punch. When I got the plate out, the holes were all kittywampus with respect to the sides of the plate, which isn't a big deal until you realize that on an engine stand the mount plate had better be pretty well centered or a top-heavy item will tumble sideways before you get a chance to clamp it. Plus, there was that worrisome error from the smaller transfer punch, along with the worry that maybe the plate slipped during punching.

When I found the actual bolt pattern, I just milled them nice and square and centered in my plate, came out just the way I wanted.

In hindsight, was it necessary? Probably not, but it *felt* safer. It isn't easy for one guy to get a J-head maneuvered up in the air to bolt it to a plate, not by half it isn't! Anything to improve the safety seemed worthwhile.

Did you see my writeup? Look at:

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GWE

Reply to
Grant Erwin

I'll offer the following alternative solution in the event that actual published specs aren't available for a future project with similar difficulties:

  1. Get a sheet of material to use as a pattern transfer that's larger than the mating face of the item in question. The sheet can be a paper product (like tag board or index card stock) or it can be sheet metal (aluminum or steel) for more demanding tolerances.
  2. Place the sheet under your item so that the sheet extends beyond the mating flange in all directions.
  3. Using either a fine pencil (I like 0.5mm mechanical pencils) on paper, or a sharp scribe on sheet metal, trace the outline of the mating flange onto the sheet. If necessary to help see the scribed lines, you can apply some layout blue first.
  4. Now you can use your transfer punches to transfer your hole positions. I doubt if 1/64" play would matter in an application like this one. (Since you're using bolts to affix the head to your adapter plate, you need a certain degree of clearance anyway in your holes. If you're transferring holes for locating dowel pins, that's another story.) Anyway, if the wobbliness of the transfer punch concerns you, and you don't have an intermediate size that will fit snuggly, here's a trick I've used that works well (although, again, I wouldn't recommend it for high-precision work): take the largest transfer punch that will fit the hole and wrap it tightly with adhesive tape to help center it in the hole. You don't want to use a soft or spongy tape (e.g., duct tape or electrical tape); I've used thin, clear plastic packing tape with success. It shouldn't take more than a couple of layers of tape to fill the gap; if it does, your transfer punch is too undersized.
  5. Now that you've transferred your pattern to the sheet, you can use the sheet to transfer the pattern to your workpiece. You can cut out the pattern if you wish along the line made around the flange, or you can make centering marks to align your workpiece on the sheet, or any number of alternatives. You can work from the front, or from the back (taking into account that the pattern will be mirror-reversed on the opposite side) as long as the marks are visible on the back side. (You may want to punch or drill small holes through sheet metal where the transfer punch marks are.)

Hope this helps.

- Michael

Reply to
DeepDiver

Very nicely written and well done. HOWEVER -

A J-head weighs about 200 pounds. Mine was sitting on a rolling dolly, oriented

90° from the way it normally sits on the mill. The bolting surface was oriented so that it was down towards the floor, and it was actually sitting on a wooden box. The belt guard hung down behind the box, and rested on a V-block. When I lifted up the front of the mill head, that meant the back, now supported at just one point, was VERY TIPPY. The combination of very tippy and very heavy made me very nervous. This is the key to my entire dilemma. I could just barely lift up the mill head and slide the plate under it, then punch it and get it out, without something horrible happening, and I felt I'd done yeoman duty when it was all done safely. I would have happily followed your procedure, or done something very similar, but for the extremely constrained circumstances.

It might have been easier later on, once I got it up in the air with the engine hoist, but then there would have been nothing to punch *against*.

I thought about just punching the holes I did mark using the transfer punch, and then using that piece as a template to mark another piece, but here my Scottish heritage came into play. Steel isn't free, far from it, and why waste one piece?

Much more satisfying and better to just drill the correct bolt pattern.

GWE

DeepDiver wrote:

Reply to
Grant Erwin

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