Bridgeport mill too tall

[Chris Richards 3Participant @chrisrichards3]

Hello,

Anyone with a Bridgeport milling machine know if I would need to remove the draw bar ever? Will all r8 tooling use the same thread as standard?

Basically I've just spent a few days dragging a Bridgeport mill into my workshop and found I don't have the head room to remove the draw bar

I know my old mill had metric threads for the ER collet holder and imperial for the clarkson auto lock.

Also if anyone knows the length of the standard draw bar I could workout if I could carve some concrete out of the floor to lower it a bit

Thanks,

Chris

[Chris Richards 3Participant @chrisrichards3]

[JasonBModerator @jasonb]

you can always tilt the head sideways

[Chris Richards 3Participant @chrisrichards3]

That is one option but would add to the setup time. Just thinking how would I tram the head with different r8 tools say an arbour for holding a fly cutter, could get complicated. Maybe I'm over worrying hopefully all my tools I buy has the same thread.

[John Stevenson 1Participant @johnstevenson1]

Should never have any reason to remove at as all R8 tooling should be 7/16" UNF.

There is some dubious M12 stuff out there made wrong but it's not special, everything should be available in 7/16" UNF.

As Jason says if you get in a serious jam, stripped drawbar etc you can spin the head to remove.

[Anonymous]

I've only removed the drawbar on my Bridgeport twice. Once when I dismantled the head to change the varispeed belt. And once to use the horizontal attachment, when the standard drawbar hex head is a bit short.

All my tooling is 7/16" UNF; although some of the import items have a rather tight thread.

Andrew

[Chris Richards 3Participant @chrisrichards3]

Thanks for clarifying that John, I can sleep tonight come to think about it, on my old machine it was a dodgy Chinese collet holder that had an m12 thread as I used a bit of threaded bar as a makeshift drawbar. Yes I suppose as Jason suggested that's kinda the option to reserve for plan b on the oddball jobs.

[Chris Richards 3Participant @chrisrichards3]

Andrew interesting to know about a horizontal attachment as I've been 50/50 as to keep my old horizontal mill or not. I'll look that up seems rare on first search?

[John Stevenson 1Participant @johnstevenson1]

We actually make Bridgeport draw bars and there are 3 models. The short hex step speed model, the longer hex model fitted to the varispeed and a longer model for the horizontal attachment.

Ours are also slightly longer by 30mm as they have two threads on the bottom and a spacer. Once one thread strips you cut it off, throw the spacer away and you have a second life.

Unlike a lot of import draw bars made in one piece ours are two piece with the thread made from high tensile steel heat treated and blacked. The top hexagon is from a different steel and thru hardened so if needed they do not mushroom over when hit. This gives you the best of both worlds and the two parts are threaded and friction welded together.

[Clive FosterParticipant @clivefoster55965]

Chris

The horizontal attachment for a Bridgeport seems to be a classic cupboard queen. Presumably due to the amount of faffing about needed to fit the thing. First change the drawbar forsooth! What were they thinking when they designed it? For most home shop and casual users there is also the cost of cutters to take in to account. Not trivial especially as there is little that the horizontal attachment can do which cannot be managed in standard mode. Maybe more slowly, maybe harder to get a good finish and maybe needing a good deal of cognition to get a set up but it does get done. In practice home shop guy almost invariably has plenty of better investments for the money. Especially as the attachment is inevitably less rigid than a proper horizontal mill so you don't have the "bury the shop in chips, fast" capabilities that makes a true horizontal so desirable.

Mine is mint with no evidence of ever having been used and, probably, on its third or fifth cupboard. Seemed like a good idea about 12 years back.

Clive.

[norm nortonParticipant @normnorton75434]

Clive – Your comment is interesting for me. I appreciate that a horizontal attachment for milling will have limited use, but do the same negatives apply to the stand alone right-angle head if you light mill with cutters up to 10mm? I am considering the Vertex one at some £350 because I have had a need to drill into jobs that are quite long/thin, when clamping horizontally will be best. Anyone have a view on the quality of these heads? they are a bit cheaper than the US imported ones.

I did not appreciate that the drawbar attachment might/will be different? Never mind as I can pull mine out.

Chris 3 – tramming is a lot easier if you make a twin dial head; it has been discussed here a little while ago.

Norm

[Anonymous]

I can vouch for the JohnS drawbars; I bought the longest one for use with my horizontal attachment. The problem is that as the quill has to be partly extended to fit the attachment the standard drawbar disappears into the head and hence is difficult to tighten. The longer drawbar has an extended hexagon section so that it doesn't disappear.

I tell a lie, I've actually used my horizontal attachment twice. Once to precision drill the centres on my traction engine crankshafts prior to machining:

And to machine V-grooves on the inside of the flats for the rear wheels, to simulate the join, as per full size:

My attachment doesn't get that much use, but like a lot of things it doesn't half make life easier when you need it. Particularly if the job will not fit on the machine in normal configuration. Anyway, you can't have too many toys.

However, I wouldn't want to use it for heavy machining. There's no substitute for a man size horizontal mill when you need to shift metal; a 5DP gear with each tooth cut in one pass:

Andrew

[Another JohnSParticipant @anotherjohns]

The nice thing about having an R8 spindle with 12mm thread form on the drawbar is that, it's hard to loan out tooling to others. (evil smile here).

Having two drawbars, one metric, the other with that UNF thread form means that one can hold just about anything.

(saying that, I don't think I have used anything other than an ER collet holder in my smaller mill, so maybe I'm not a good example to follow)

[John McNamaraParticipant @johnmcnamara74883]

Hi Chris

Changing drawbars… Mine is a rather tight fit too. I find if I drop the quill down this moves the end of the spindle shaft with the drawbar hole lower, allowing the drawbar to tilt sooner and clear the ceiling. I can just get my longest drawbar out without having to tilt and then reset the head itself.

Regards
John

[MuzzerParticipant @muzzer]

Slightly envious of you R8 boys. My Taiwanese clone has the 30 taper spindle. Because there isn't as wide a choice of compatible tooling compared to R8 or even 40/50 taper, I have to be able to accommodate both metric and imperial threaded toolholders. That's what led me to develop my own quick change tool holding system. It's pretty quick and easy (or was last time I was actually able to use it) but the downside is I need to fit custom pull studs to my tools.

I'd be sorely tempted to buy a load of Tormach Tool System toolholders if I had an R8 spindle. That way you wouldn't ever(?) need to change the collet and you could leave the tools set up in their holders.

Murray

[Bob Unitt 1Participant @bobunitt1]

I had this problem with my Myford VMB mill. It was delivered to my ground-floor workshop (bedrooms above) with the drawbar in place, and when I came to try and take it out it hit the ceiling first. I eventually got round it by cutting a hole in the plasterboard of the ceiling and pushing in a bit of drainpipe to hold back the insulation – the drawbar then came out OK, clearing the floorboards of the room above with about 1/4" to spare.

[Author]

Posts