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View Full Version : Bridgeport NMTB30 to Erickson Quick Change conversion



KEJR
10-19-2012, 08:34 PM
I have a bridgeport machine with the NMTB 30 taper spindle and what looks like a threaded protection collar over it to keep hands away from the anti-rotation blocks that key in the tool holder. I have a power drawbar which is not too bad except the unit doesn't fit my low garage ceiling. I'm thinking to see if I can screw on an Erickson style quick change collar to adapt it to that system. I know bridgeport sold alot of machines with the Erickson rig, so it would make sense for them to use the same spindle/thread for all the 30 tapers, but I don't know for sure. Does anyone have experience with this? Any recommendation on part numbers I would need for the conversion?

I'm not totally hosed, I could excavate some drywall in my ceiling and have the power drawbar poke through, but tilting operations (although infrequent) would get a bit hairy.

I really don't want to go to a manual drawbar since the machine has a Z axis head that would require a large step stool to reach!

EDIT: The machine is a 1984 Bridgeport V2E3

Thanks,
KEJR

john hobdeclipe
10-19-2012, 10:16 PM
My J head Bridgeport has Erickson Quick Change. Fortunately, it also has a hollow spindle (I understand that some of the Quick Change spindles are solid.) I've learned that it's relatively easy to find basic 30 taper tooling but somewhat harder to find it with the proper flange to work with the Erickson system. I made a drawbar for mine, and I can use most any 30 taper tooling that I find (I've bought 3 toolholders recently from Travers, and they seem just fine to me.)

Victor (one of the advertisers on this site) says to call them if you need Ericson 30 tooling. I never did, since I have the drawbar on mine now. http://www.victornet.com/alphabetic/30-40-50-NST-Tooling/271.html

The special nut for the Erickson spindle has a retaining system inside. I'll measure mine tomorrow and maybe get a pic, and try to post it here for you.

I THINK, but don't know for sure, that you can make a self ejecting drawbar that does not require room overhead to tap it to loosen it.

legendboy
10-19-2012, 11:54 PM
I pulled mine off and snapped a picture of it

Major mic'd at 2.372" o.d. and 16tpi

Let me know if you want any other measurements or pics

Cheers

http://www.telusplanet.net/public/shackner/R2E3/spindle%20thread.JPG

legendboy
10-20-2012, 12:03 AM
and the nut i have been meaning to clean

http://www.telusplanet.net/shackner/R2E3/erickson%20nut.JPG

BigJohnT
10-20-2012, 06:47 AM
Mine came with a Kwik Switch 200 spindle (http://www.ebay.com/itm/UNIVERSAL-KWIK-SWITCH-200-SPINDLE-BRIDGEPORT-MILL-/150925601937?pt=BI_Tool_Work_Holding&hash=item2323ddec91) which is solid and doesn't stick out the top any and I've seen them from time to time on flea bay. Works well and tooling is not expensive. Just don't get the DA collet ones as they are terrible. You can usually change holders without any tools just a twist of the nut and it falls out and when you put the next one back in it locks by itself.

John

KEJR
10-20-2012, 08:06 AM
I pulled mine off and snapped a picture of it

Major mic'd at 2.372" o.d. and 16tpi



LegendBoy, you be da man. Seriously, thanks. I'm glad I could give you an excuse to clean the collar! :D

I'm going to go measure my spindle collar nut later on this morning (My little ones are up, need to feed them).

KEJR

KEJR
10-20-2012, 08:11 AM
Mine came with a Kwik Switch 200 spindle which is solid and doesn't stick out the top any and I've seen them from time to time on flea bay. Works well and tooling is not expensive. Just don't get the DA collet ones as they are terrible. You can usually change holders without any tools just a twist of the nut and it falls out and when you put the next one back in it locks by itself.
John

I think we have the Kwik Switch 200 at work on one CNC bridgeport and some other machines. I already have some carbaloy brand 30 taper holders that take DA collets that came with the machine. Just curious, but what don't you like about the DA setups? Another guy I was talking to likes them better than ER just because they have smaller nuts for the given collet size.

I was hoping my carbaloy holders are QC30 compatable but I probably won't know until I try them out.

KEJR

KEJR
10-20-2012, 08:22 AM
My J head Bridgeport has Erickson Quick Change. Fortunately, it also has a hollow spindle (I understand that some of the Quick Change spindles are solid.) I've learned that it's relatively easy to find basic 30 taper tooling but somewhat harder to find it with the proper flange to work with the Erickson system. I made a drawbar for mine, and I can use most any 30 taper tooling that I find (I've bought 3 toolholders recently from Travers, and they seem just fine to me.)

This is definitely a consideration, although I've seen quite a few erickson compatable products on flea bay. I suppose if my threads measure up to what LegendBoy posted and I can find a cheap collar I'll just get it and try it. If I need the oddball tool with a drawbar, I just can use a wrench for those occassions.


I THINK, but don't know for sure, that you can make a self ejecting drawbar that does not require room overhead to tap it to loosen it.

I've looked at these for R8 style collets where the premise is to leave in the 3/4 collet and retain it with some stiff washer springs. The idea is you click the drawbar up against a block to compress the springs and it releases the collet. I think for the nmtb you would need something that screws in like a drawbar, or one of those hydraulic retainer knobs (which is probably out of my price range to get working!). If you know of another idea I haven't seen I wouldn't mind knowing about it.

Thanks
KEJR

KEJR
10-20-2012, 09:15 AM
and the nut i have been meaning to clean



One more question. In operation does this collar rotate and tighten on the screw thread of the spindle? It looks like from this picture that the screw thread and outer knurled collar piece are in fact one piece. If this is the case does the little button head screw limit rotation to a quarter turn, and if so should I look for a 90degree milled groove/slot in the spindle threads (For the button head screw), or does it work differently than that?

Thanks,
KEJR

KEJR
10-20-2012, 03:36 PM
I just wanted to mention that I seem to have the same exact thread as LegendBoy. after removing the two jam set screws (wiht nylon plugs underneath) I was able to remove the protective spindle thread collar with a strap wrench. It measures 2.373"ish and a 16TPI screw I had laying around meshed perfectly in the threads.

My spindle *JUST* has a thread like in LegendBoy's photo (It looks exactly the same, in fact). As long as it looks like that all around I think I'm in business and can just purchase the part from somewhere.

Thanks,
KEJR

BigJohnT
10-20-2012, 03:54 PM
I think we have the Kwik Switch 200 at work on one CNC bridgeport and some other machines. I already have some carbaloy brand 30 taper holders that take DA collets that came with the machine. Just curious, but what don't you like about the DA setups? Another guy I was talking to likes them better than ER just because they have smaller nuts for the given collet size.

I was hoping my carbaloy holders are QC30 compatable but I probably won't know until I try them out.

KEJR

The DA don't pull the collet out of the holder like the other ones do and I was told they don't hold center as well as the ER type. I have a couple I purchased by mistake and if you end up with a Kwik Switch 200 spindle I'll give them to you, you pay the postage.

John

john hobdeclipe
10-20-2012, 06:17 PM
Legendboy has already provided pix and measurements, so i won't repeat that. But here is a pic comparing the Quick Change 30 toolholders with other 30 taper toolholders. On the left are a drill chuck and a double angle collet holder for the Quick Change system. To the right of that is a 1/2" end mill holder, a boring head holder, and a 3/4" end mill holder all in NMTB30, and on the right, for comparison, is a 1/2" end mill holder in R8.

The NMTB30 holders shown here won't work with the Quick Change collar because there's no place for the prongs inside the collar to grip and pull the holder into the spindle.

http://www.auldooly.com/imagehost/PA200005-12.jpg

Here's how I worked out the drawbar on my machine. Yours may or may not work the same:

Mine has a hollow spindle with a bore just large enough to clear a 7/16" rod. But the thread on the 30 taper tooling is 1/2 - 13. So I drilled a 5/16" hole in a piece of 1/2" bolt, turned down the end of a piece of 7/16" rod, and brazed the threaded piece on. I inserted this into the spindle from the bottom, experimented a bit with the length (with a toolholder in place) and marked the top of the rod at the top of the spindle. Then I took it out, slipped on a piece of 3/4" hex stock that had a 7/16" hole in it already, and drilled for two roll pins. Then re-insert the drawbar into the spindle, hold it in place with a toolholder, and slip the hex stock on from the top. Squeeze in the two roll pins and it's ready to go.

What I learned inadvertently is that when I loosen the drawbar and give it another turn or so, the section of 1/2" thread moves up against the top of the socket, where it goes from 21/32" down to about 7/16" and if I keep turning, it pops the toolholder loose.

I don't use this "feature" routinely because I don't like the feel of steel on steel inside the spindle. But I'm going to take the drawbar back out and install a brass or bronze washer and try that. I think it will work, especially if I keep some oil on it.

KEJR
10-21-2012, 08:32 PM
I have a bunch of DA holders like the one you have shown. I'm pretty sure they are QC30 compatable. I already have a drawbar in mine with a pneumatic gizmo on it. I just want to try and not have to cut into my ceiling just to get the mill head fully upright!

Anybody have any idea what the QC30 collar/nuts are worth anyway?

legendboy
10-22-2012, 12:18 AM
One more question. In operation does this collar rotate and tighten on the screw thread of the spindle? It looks like from this picture that the screw thread and outer knurled collar piece are in fact one piece. If this is the case does the little button head screw limit rotation to a quarter turn, and if so should I look for a 90degree milled groove/slot in the spindle threads (For the button head screw), or does it work differently than that?

Thanks,
KEJR

KEJR,

The collar and nut are one peice as you describe

http://www.telusplanet.net/shackner/R2E3/erickson%20nut%202.JPG

The tool retaining component is all one piece being held in place by a c clip.

I believe what makes the erickson system work is a specific tool holder flange thickness.

The screws limit rotation using the stops on the bottom of the spindle. There is likely an instruction for reassembly in the manual to get it set right. I can post those instructions if you want.

I think you can buy the erickson nut and thats all you need.

There was one I had watched for a while on ebay but it appears to be gone

There is one you could try and snipe!

http://www.ebay.com/itm/NEW-KENNAMETAL-ERICKSON-NMTB-30-QUICK-CHANGE-30-TOOL-HOLDER-COLLAR-WRENCH-/360498659694?pt=BI_Tool_Work_Holding&hash=item53ef65016e

Jaakko Fagerlund
10-22-2012, 03:45 AM
What I learned inadvertently is that when I loosen the drawbar and give it another turn or so, the section of 1/2" thread moves up against the top of the socket, where it goes from 21/32" down to about 7/16" and if I keep turning, it pops the toolholder loose.

I don't use this "feature" routinely because I don't like the feel of steel on steel inside the spindle. But I'm going to take the drawbar back out and install a brass or bronze washer and try that. I think it will work, especially if I keep some oil on it.
Just use it as such, don't put that bronze or brass there, as they tend to shed small shavings/chips and then your spindle bore and/or tooling is littered with them over time.

The thread end pushes in to a place where it doesn't matter in the spindle.