Some Bridgeport Questions

[brownac1983]

Hey guys,
There's a big machine shop auction coming up near me and they have some Bridgeports there. I've been in the market for a milling machine for a while but I've been looking in the bench mill market due to space limitations. I've decided that if one of these in decent shape can be had for a reasonable price that I'm willing to commit the floor space. One of them in particular has caught my eye, and I have a few questions to help me decide if it's right for me.

The machine in question is described as a 9"x36", 1HP, variable speed up to 2,720RPM. It appears to be a J-head when I compare the pictures to the lathes.co.uk web page.

This is the only one that they have of this size, the rest are all 9"x42" or 10x50". The smaller size appeals to me, as well as the all-manual table (this disagrees with a lot of recommendations I've read, but my target is the occasional small one-off task).

I have a few questions about these, I've used them before but only occasionally and it's been a while:

1) If it is truly variable speed (instead of just pulley changes), does that mean that it has a VFD (I suppose it would have to)?

2) Besides the normal things that I'd look for on a lathe (way wear, slop, excessive backlash, strange running noises, smoothness of controls), is there anything special that I should be on the lookout for?

3) The round removable handwheel for fine feed is missing, is that cause for concern? How easy are those to find?

4) Are all J-heads R8 taper?

If I were to get it (and that's still a huge IF at this point), my plan for moving it would be to flip the head over and position the knee to get the lowest center of gravity, and then have them load it on the trailer. There are professional riggers on site that will load it for a fee (only pro riggers are allowed to load on site), but my main concern is setting myself up so that I can unload it as safely and easily as possible. I'll be unloading onto a concrete slab that I can back a trailer up to. The plan that I came up with is to rent a drop-deck trailer and pallet jack, have them load it on the trailer on a heavy duty pallet, back the drop deck trailer up to the slab and lower the deck, then just pallet jack it off of there. All of this with at least 3 helpers in case things get tippy. This leads me to a couple more questions:

5) Does that sound like a reasonable plan? I've moved large equipment (machinery, safes and such in the same weight range) plenty but never one of these. Any pitfalls I should look out for besides the obvious top-heavy issue?

6) What would you consider a fair price to load it on a trailer? I plan to call and ask the rigging company beforehand, but I have no idea what a ballpark fair price would be? They'll already be on site.

Sorry for the lengthy read. Any advice is appreciated.

-Drew

 

[Ed ke6bnl]

I am willing to bet it is belt change, I just moved mine around with a pallet jack, watch sharp turns tippy, can lower the table and turn head upsidedown to help get CG lower. I used that to move around garage but use a homemade gantry to unload. It now resides on a metal plate with legs and can easily be moved with pallet jack. Good luck. A lot of auction places have a forklift to load on your trailer, try calling them. 3 phase so you may need rotary phase converter or VFD?

 

[Bob Korves]

1. If it is 2720 RPM top speed, it is a step pulley/back gear design where you change the belt for different spindle RPM's, Eight speeds, four in direct, four in back gear. That size table and machine is great for a small shop and occasional use if you have the space for it. It is likely 3 phase, but verify, if so you will need 3 phase power or a VFD or other phase converter.

2. You have listed the important ones. Work all the levers and knobs for smooth motion and for the ways not tightening near the end of the travel or sloppy in the middle.

3. The fine feed handwheel is commonly removed as a safety and convenience change. They get lost often and can be found used if you really want one. Most users do not.

4. That machine should be R8, but verify. Usually only the older round ram machines or the really big machines have different collet tapers.

5. Your plan sounds totally reasonable. The machine is quite top heavy, don't let it get away from you.

6. It sounds like you are a captive audience to the designated riggers. Yes, call for the pricing and factor it into your bid price maximum.

 

[JimDawson]

1) If it is truly variable speed (instead of just pulley changes), does that mean that it has a VFD (I suppose it would have to)?

The 2720 max RPM would indicate change belts, to have true variable speed would require a VFD on that machine.

2) Besides the normal things that I'd look for on a lathe (way wear, slop, excessive backlash, strange running noises, smoothness of controls), is there anything special that I should be on the lookout for?

I think you have it covered. Way wear is the most important, you can replace the lead screw nuts for a reasonable amount if needed. A spindle rebuild is about $600 by a reputable rebuilder if needed. The rest of the head is inexpensive to rebuild. Hopefully the machine is under power so you can hear it run.

3) The round removable handwheel for fine feed is missing, is that cause for concern? How easy are those to find?

I have only seen 3 machines that actually had that handle, and I bought all of them new! I have never actually used the handle in about 45 years. I'm sure they are available, or would not be difficult to make if you really needed one.

4) Are all J-heads R8 taper?

Most are with very few exceptions.

If I were to get it (and that's still a huge IF at this point), my plan for moving it would be to flip the head over and position the knee to get the lowest center of gravity, and then have them load it on the trailer. There are professional riggers on site that will load it for a fee (only pro riggers are allowed to load on site), but my main concern is setting myself up so that I can unload it as safely and easily as possible. I'll be unloading onto a concrete slab that I can back a trailer up to. The plan that I came up with is to rent a drop-deck trailer and pallet jack, have them load it on the trailer on a heavy duty pallet, back the drop deck trailer up to the slab and lower the deck, then just pallet jack it off of there. All of this with at least 3 helpers in case things get tippy. This leads me to a couple more questions:

5) Does that sound like a reasonable plan? I've moved large equipment (machinery, safes and such in the same weight range) plenty but never one of these. Any pitfalls I should look out for besides the obvious top-heavy issue?

Sounds like a well thought out plan. Just be careful when coming off of the drop deck to the concrete, there is still a pretty sharp transition there, about a 4 inch drop. Control the decent with a come-a-long attached to the front of the trailer. I have moved a lot of machines on a drop deck and they work well. As stated above, pallet jacks get tippy on sharp corners, be careful. Bolt the machine to the pallet with lag screws if possible.

6) What would you consider a fair price to load it on a trailer? I plan to call and ask the rigging company beforehand, but I have no idea what a ballpark fair price would be? They'll already be on site.

I dunno. At auctions, these guys charge premium prices because the have a captive audience. It sounds like you really don't have a choice, and what ever they charge is probably less than bringing in your own riggers. Don't be afraid the negotiate with them.

 

[brownac1983]

Thanks guys, your insight is very much appreciated.

I'll have to verify, but I believe everything will be under power on inspection day, and before the auction they'll have someone remove the wiring from the machines.

I agree with the above points about the riggers. Hopefully they won't beat me up too bad, but I'm pretty much at their mercy unless I want to pay someone else a trip fee.

Hopefully it's a good auction. Used Bridgeports are pretty cheap where I'm at, I see them in the $1500 range a lot, so hopefully I can beat out the resellers and get myself a good deal. They have plenty of R-8 collets and tooling available separately, so I'll have to pick up some of that as well.

Thanks again for answering my questions. I'll let you know if it's a go or no-go by end of next week. Here's a screenshot of the machine in question:

 

[TakeDeadAim]

I looked at several machines locally looking for a machine this size and went to a couple auctions as well. All the machines I found were well used shop machines that all needed work. I worked rebuilding machine tools for several years and know the hours involved and the money it costs to replace parts. I would suggest adding up what you need to spend to bring the machine to the condition you want for your shop.

So using your list so far; Cost of machine, Riggers fee, Trailer rental, Three phase converter or VFD?, Needed repairs?, Time for clean up and adjustments

I hope you can do better than I did. Every machine I looked at needed something fixed or replaced, All the smaller table machines had beat up tables that would need a re-grind and they all needed a really good bath! and re-scrape, re-fitting of the gibs.

In the end a new PM1136 and a VFD from Matt at Quality Machine was less than a used machine. The freight company put it on the trailer for me and my existing gantry crane got it off the trailer and set it in place.

Like I said I hope your situation is better than I had but I'd be sure and take my calculator with me before I raised my paddle. Let us know how you did and if you need help with with any repairs, please let me know. I've been there and done that many times and would be happy to help you get something you find into good working shape.

 

[TakeDeadAim]

You posted your photo while I was writing, That is for sure a belt change machine, its been re-painted but I don't see anything falling off. If they sell for around $1500 that is about a $1000 less than what I could find around here. Good luck!

 

[jmarkwolf]

As for R8 question, borrow or buy a cheap R8 collet, take it to the auction and make sure it fits before you bid.

Look in the side door on the column. You might find the hand wheel in there. I found the hand wheel and the knee crank in there when I bought my 9x42.

The mill in the pic is indeed a step pulley. A VFD will make it a variable speed. You'll need a VFD or similar to make 3-phase anyway.

EBAY has loads of parts for Bridgeports.

 

[brino]

Hi Drew,

It sounds like you've done your homework and have very realistic expectations.

Used Bridgeports are pretty cheap where I'm at, I see them in the $1500 range a lot

That price seems low for my area too, but if you can get it around there you'd be doing well.
I have found that at auctions prices vary wildly with the people there that day....something you have absolutely no control over.

Good Luck and be careful with the unloading!
-brino

 

[brownac1983]

Thanks guys. I'll let you know how it turns out. The market around here is fairly soft on used machinery, unfortunately that's a result of a lot of machine shops closing. There are some resellers that buy them and mark them up, but they tend to ignore older machines, especially those without power feeds and DROs.


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