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Machine Shop and Tool Talk

Getting a Bridgeport ready to go


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  #21  
Old 01-11-2016, 02:11:40 PM
rennkafer rennkafer is offline
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Default Re: Getting a Bridgeport ready to go

An inner race from a large bearing works quite well for a tramming ring too.
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  #22  
Old 01-11-2016, 06:22:39 PM
Amax Amax is offline
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Default Re: Getting a Bridgeport ready to go

Those are both good ideas.

Well, last night I went to use this beast for the first time. I was whittling a metal bracket for something.

I could not get the drawbar to grab the collet. Actually, I could feel the drawbar begin to engage the collet but then it would lock up and I could not tighten it any.

I was pretty bummed. Because I was in a hurry, I did not do much investigating.

What can I check before i spin the head 90 degrees to get the drawbar out (cutting a hole in the ceiling is not an option)?

I ended up carving my bracket with a rotary burr. The Bridgeport was major overkill for this job, but I did want to finally use it.
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  #23  
Old 01-11-2016, 08:44:10 PM
rennkafer rennkafer is offline
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Default Re: Getting a Bridgeport ready to go

You could find a bolt with the same thread as the drawbar and check that the threads in the collet aren't the problem. Also, assuming it's an R8 spindle, make sure you've got the pin inside the spindle lined up with the slot in the collet when you try to screw the drawbar in. If it isn't it will cock sideways and not go up into the spindle far enough to seat.
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  #24  
Old 01-11-2016, 10:41:10 PM
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Default Re: Getting a Bridgeport ready to go

Is your collet new or used? I bought a new 11/16" collet (brand X China) and had the same problem. Drawbar would screw in fine when out of the spindle, but not when in the spindle. After some head scratching I found the collet was taped crooked not letting the drawbar screw in when held straight by the spindle.
The supplier sent me a new one no charge and let me keep the bad one.

PT
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  #25  
Old 01-11-2016, 10:57:00 PM
Amax Amax is offline
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Default Re: Getting a Bridgeport ready to go

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Is your collet new or used? I bought a new 11/16" collet (brand X China) and had the same problem. Drawbar would screw in fine when out of the spindle, but not when in the spindle. After some head scratching I found the collet was taped crooked not letting the drawbar screw in when held straight by the spindle.
The supplier sent me a new one no charge and let me keep the bad one.

PT
It is a used collet that I am pretty sure came with the machine. I will take the collet out as suggested. Not sure how I can check the end of the drawar without swinging the head (only have a couple of inches above the machine to the ceiling).
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  #26  
Old 01-12-2016, 07:24:42 AM
wmusta wmusta is offline
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Default Re: Getting a Bridgeport ready to go

The hex may be pinned to the draw bar shaft. Can you raise drawbar high enough to remove pin/hex assy. Then you can lower drawbar shaft down though center of spindle for inspection or removal.
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  #27  
Old 01-12-2016, 04:34:42 PM
Amax Amax is offline
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Default Re: Getting a Bridgeport ready to go

I spun the head to remove the drawbar, and I think I have found the problem. There was no washer on the drawbar. That probably is not good for the end of the quill; it is what was preventing the collets from being held fast.

Is there a problem with me just throwing a spacer in there? Or do I need to turn it accurately? I'm guessing the washer should be around 3/8" thick since I was getting about a 1/4" of vertical play at the collet when the drawbar was cinched down.

If anyone has the proper dimensions for this washer, please post them up.
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  #28  
Old 01-12-2016, 05:42:16 PM
Amax Amax is offline
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Default Re: Getting a Bridgeport ready to go

I was anxious to make chips so I resorted to cave man tech.

I found two spacers - one 1/4" and the other 1/8" - that fit loosely over the draw bar but with an OD small enough to fit inside. I was able to squeeze an o-ring around the drawbar and inside the lower spacer to keep things together the next time I remove the drawbar.

The collet and end mill tightened up just as they should. Cranked the head up to 0 degrees (nothing has been trammed yet).

I grabbed the first piece of metal I could find and crudely made some chips using my cheap drill press vise.

That's it for today.

I will eventually need the proper washer but first I need a milling machine vise as sadly this machine did not have one. That might take a while because even though they are not that expensive these days, I am for the time being on an austerity budget.
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  #29  
Old 01-12-2016, 07:35:41 PM
prybar prybar is offline
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Default Re: Getting a Bridgeport ready to go

15 years ago I bought a new bp. Had them set it up for a 30 degree quick Change. No draw bar, change tools in a second. My cnc, Bridgeport, and Cincinnati tool master are all the same.
Should not be hard to change over. Just a thought.
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  #30  
Old 01-12-2016, 10:40:32 PM
Amax Amax is offline
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Default Re: Getting a Bridgeport ready to go

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Originally Posted by prybar View Post
15 years ago I bought a new bp. Had them set it up for a 30 degree quick Change. No draw bar, change tools in a second. My cnc, Bridgeport, and Cincinnati tool master are all the same.
Should not be hard to change over. Just a thought.
That would be cool. Unfortunately, as infrequently as I use it and since for the time being I am flat broke, not likely an indulgence I could enjoy.

It also sounds like you are in a higher league than I when it comes to one's personal shop. Kudos.

This was the first time I'd ever encountered a problem like this. I guess it was the combination of a 'new' (unused by me) machine and my low ceiling height that discouraged removal of the drawbar. I am not sure why that spacer/washer was missing, but it was.
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  #31  
Old 01-14-2016, 01:51:08 PM
rennkafer rennkafer is offline
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Default Re: Getting a Bridgeport ready to go

Quote:
Originally Posted by prybar View Post
15 years ago I bought a new bp. Had them set it up for a 30 degree quick Change. No draw bar, change tools in a second. My cnc, Bridgeport, and Cincinnati tool master are all the same.
Should not be hard to change over. Just a thought.
I have both a QC30 and an R8 spindle for my BP head and (since it's apart to rebuild) have been trying to decide which spindle to use. The QC30 looks convenient, but the tooling is way more expensive/more difficult to find.

Where do you find tooling that's not outrageously priced compared to R8?
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  #32  
Old 01-14-2016, 03:40:08 PM
Amax Amax is offline
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Default Re: Getting a Bridgeport ready to go

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Originally Posted by rennkafer View Post
I have both a QC30 and an R8 spindle for my BP head and (since it's apart to rebuild) have been trying to decide which spindle to use. The QC30 looks convenient, but the tooling is way more expensive/more difficult to find.

Where do you find tooling that's not outrageously priced compared to R8?
I wouldn't know but some of these guys will. I only have R8 tooling.
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  #33  
Old 01-14-2016, 07:56:07 PM
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Default Re: Getting a Bridgeport ready to go

Amax, I used my BP today to drill out a broken bolt in an exhaust manifold and when I took the chuck out to gain clearance to chase out the other holes, I remembered your situation. I pulled out the drawbar and measured the spacer. It appears to be hardened, but for your limited use I doubt that it will matter.
OD: 1"
ID: .5"
Thickness: .312"

PT
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  #34  
Old 01-16-2016, 11:43:35 PM
redlee redlee is offline
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Default Re: Getting a Bridgeport ready to go

Why not just "Tram" the table, been doing it for 35 years and its the most accurate way.
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  #35  
Old 01-17-2016, 12:53:40 PM
dkamp dkamp is offline
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Default Re: Getting a Bridgeport ready to go

Just to be the devil's advocate, I suggest visiting an antique store, and 'buying' a nice 'steamer trunk' or perhaps a cedar chest... and look... a rope-type block-and-tackle, with authentic hemp rope, and a couple of big iron screw-hooks! Flip the chest upside down, cut the bottom out of it, and set it on the floor directly over the BP... THEN saw a hole through the floor/ceiling. Install a light in it, while you're at it- always nice to have light inside your trunk, and above the mill. Then screw the hook into the ceiling above the chest, hang the block and tackle... and swing it off to the side, put another hook in the wall, and hang the bottom end there. Now you have a decoration, that when necessary, flip open the 'trunk', drop the hook down, and lift your mill head off!!!



Question is, how often will you actually HAVE to pull the drawbar. I've probably had mine out... twice in ten years or so.

Another possibility, is make it so that you have a drawbar who's top nut disengages from the bar, so that the bar will drop DOWN and out of the spindle AFTER you've removed the tooling. Obviously, the top nut engagement needs to be robust enough so that drawbar torque and tension won't break it off, but we're all machinists here, right?
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  #36  
Old 01-17-2016, 01:05:37 PM
beezerbill beezerbill is offline
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Default Re: Getting a Bridgeport ready to go

Tramming the table is a really good approach as long as you are certain the table itself is flat and true to the machine. I had one machine where this wasn't the case - the table was wedged in the Y direction by about .002 across the width of the table. Also many older tables are all boogered up - you can stone out any "high" boogers but the craters are more of a problem. And you have to remember to lift the indicator tip over the T slots so you don't crash it. Still it is better to indicate off the table than to introduce another element (tramming ring) that could introduce its own error.

Checking the table is easy - just put your indicator against it and run the machine along its X direction and watch what the indicator does as you go from one limit to the other. This will show any distortion in the table, as well as any "barrel" wear in the ways. Then do the same thing in the Y direction (lifting the probe tip as you cross the T slots). You can also grab the end of the table and lift on it as you probe the length of the table - this will show any looseness in the ways. Do all this before you tram.

One sure way to guarantee a flat surface is to bolt a sacrificial aluminum jig plate to the table using counterbored screws, and them mill the top of the jig plate flat. Don't worry about tramming yet but do use small steps as you move your cutter across the plate so that any tilt in the cutter face (due to the head not being trammed yet) doesn't result in any significant stepping across the plate. If done right, you now have a jig plate that is true to the X and Y travel that you can tram against or even leave on the machine, and drill holes in and bolt stuff to until it is so chewed up you can't use it anymore - then replace it with a new one. Once the head IS trammed it is easy to flycut any new jig plates.

In proofing this post I ran across a sentence that describes my fellow Boulder residents as much as it does any shop practices but I thought I would leave it anyway - can you pick it out?
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