Author Topic: Advice on buying a vertical mill.  (Read 7652 times)

Offline Manorfarmdenton

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Advice on buying a vertical mill.
« on: February 17, 2018, 09:51:45 AM »
I wonder whether anyone can help with advice on buying a lathe or mill?  I have an ancient mill to which I have fitted DROs to eliminate the issue of backlash, and a countershaft to give lower speeds for larger mills and drills, a boring head etc.  BUT the 3MT spindle runs reasonably truly at times and at others has a distinct wobble!  The old lady was manufactured in 1943 according to the plate, and I paid £300 for it in the early 90s so it doesn't owe me anything.

I also have a Colchester Bantam 2000 lathe bought second-hand at the same time.  This has a worn bed, so if the gibs are tightened so the saddle is relatively accurate near the chuck it becomes far too tight towards the tailstock end of the bed.  A lot of it is my fault as I have abused it by turning 5" round down to make stub axles for agricultural machinery, have held a combine drum shaft in the chuck with the 'tailstock' end sitting in an oak block on a tool chest way off the end of the lathe, etc, etc.

All this doesn't really matter for a lot of the things I do, cross-drilling 40mm round for split pins, opening up the centres of cast wheels to take the 40mm spindles etc (just a job I'm doing at the moment).
However, in my dotage I have started making models and a wobbly spindle is significant when drilling 1mm cross-holes in 2.5mm pins for the governor on the RLE engine I have nearly finished.

I have a little mini-lathe, bought new a year or two ago, so my main 'want' is a better turret mill.  Presumably a slightly bigger one is more rigid, so what do the experts think about a secondhand Bridgeport?  There seem to be lots on eBay for around £4K, but I'm wary of spending money only to find there isn't much improvement over my old one.  It would be lovely to have power feed to the odd axis, and a better way of changing speed - at the moment I have to slacken and swap vee belts etc.  Any advice gratefully accepted!

John.
John Fearnley

Offline kvom

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Re: Advice on buying a vertical mill.
« Reply #1 on: February 17, 2018, 12:38:52 PM »
I have a Bridgeport from the 60s that is a fine machine.  4K for one is expensive around here, but I suppose supply is more limited over there.

I use a VFD for speed control so no belt-switching.  Plus some J-head machines have variable speed.

Online Jo

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Re: Advice on buying a vertical mill.
« Reply #2 on: February 17, 2018, 02:42:40 PM »
£4K will buy you a very nice Bilgeport with every bit of kit under the sun or an even better milling machine. But it is a bit risky buying off Fleabay.

Try phoning the Sidcup boys: http://www.homeandworkshop.co.uk/index.html?21129 and see what they have to offer (they deliver).

G&M have some very nice ones on at the mo: http://www.gandmtools.co.uk/product-category/machine-tools/milling-machines-engravers-jig-borers/

Jo

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Offline Manorfarmdenton

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Re: Advice on buying a vertical mill.
« Reply #3 on: February 17, 2018, 02:43:42 PM »
Kvom - thanks for replying.  I only mentioned £4k because I had been looking on eBay.  Presumably I could find a supplier not too far from home and have a look, although how one establishes whether there's wear I'm not sure?

Having said my old lady doesn't run truly, the reason this time for the wobble in the collet chuck is my breaking off a 10mm long-reach end mill the other day.  Because there's a lot of room in lead-screws etc the table sometimes jumps a few thou, and that was what happened!  Anyway, I knocked the chuck down and re-seated and re-tightened it and its true again.  I drilled the 1mm holes through the 2.5mm pins with no problem.  I think I probably need to get the 3MT socket in the spindle re-machined, but it isn't worth it on such an ancient machine.

John.
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Offline Manorfarmdenton

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Re: Advice on buying a vertical mill.
« Reply #4 on: February 17, 2018, 02:46:23 PM »
Thanks Jo!  I agree about the danger of buying off eBay - I've been caught several times over the years.  A recommendation is what I was hoping for!

John.
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Online Alyn Foundry

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Re: Advice on buying a vertical mill.
« Reply #5 on: February 17, 2018, 03:59:02 PM »
Hi John.

I may be considered biased by some but before my health issues I worked for Chester UK. Now known as Chester Machine tools.

In the workshop we used a Bridgeport " copy " known as the 1065. This machine had been returned to the works because of an accident in transit.

I found this machine to be amazingly accurate and believe it or not, stronger too!

When I last visited the works the old gal is still being used by the present keeper and going strong.

As a by the way, when did you last look at the spindle bearings on your machine? Perhaps the preload needs attention, just a thought?   ;)

Cheers Graham.

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Re: Advice on buying a vertical mill.
« Reply #6 on: February 17, 2018, 05:36:14 PM »
Make sure the mill has good geometric accuracy.   By that I mean flat  square and parallel.       You can do good work with a worn lathe but a worn mill can be really detrimental to good work and enjoyment.      A good mill vise is also very important.     
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Offline Manorfarmdenton

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Re: Advice on buying a vertical mill.
« Reply #7 on: February 17, 2018, 07:19:21 PM »
A local clock/model maker - he used to be a toolmaker with Ford - has recommended and has in his workshop a Bridgeport, which is why I started looking at them. 
Jo has suggested a couple of sources as you see - I too am wary of ones on Ebay - and G & M have got some nice looking examples of various makes for less money than I was thinking.

I wonder about the pre-load on my spindle bearings too Graham.  That's something I can look at, but it won't alter the fact that I've begun to hanker for something a bit more sophisticated!  :)

Steamer, the vice is another issue.  Mine was bought new but does have the odd thou rise on the movable jaw when its tightened.  I usually knock the workpiece down tight onto the parallels with a soft-faced hammer.
John Fearnley

Offline jadge

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Re: Advice on buying a vertical mill.
« Reply #8 on: February 17, 2018, 09:45:00 PM »
I've got a varispeed head Bridgeport, bought from G&M some 12+ years ago. I paid £2k, which in retrospect was a bit over the odds. My machine has the DC motor X-axis power feed, which is very useful. My machine is pretty worn, 15-20 thou of backlash, but the DRO takes care of that. After years of struggling with a machine vice thrown in as deal sweetener I finally bought a Kurt. Expensive, but good and on the numbers. You simply don't need to worry about parallelism and jaw lift. My Bridgeport has the 48" table, and I have run out of travel on occasion.

I have bought machine tools from Ebay, a power guillotine and a cylindrical grinder, but they were from established dealers who had a presence outside Ebay. Both were bought some years ago. I think Ebay has changed considerably over the years. There now seem to be many more chancers asking silly money for dubious kit. A Bridgeport is a bit delicate in the spindle power feed area, so personally I'd like to see one I bought running to check function and noise. The varispeed heads can be quite noisy. Mine certainly is!

Andrew

Offline Manorfarmdenton

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Re: Advice on buying a vertical mill.
« Reply #9 on: February 17, 2018, 11:23:56 PM »
As you say Andrew, backlash isn't a great issue if you've got DRO, but I'm concerned that an oldish machine may have wear in the slideways, given that my Bantam 2000 doesn't turn parallel any more because of wear in the bed.  The cylinder bore of little engines like my Red Wings can be as much as .003" different from one end to t'other! 

Presumably buying from a reputable dealer like G & M gives some sort of assurance though.  I'll give them a ring as Jo suggests.

John.
John Fearnley

Online steamer

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Re: Advice on buying a vertical mill.
« Reply #10 on: February 18, 2018, 02:01:43 AM »
Any easy check to see if you probably have a worn mill   with the table in the center of travel, nip up the hub lock to almost tight.....then move the table to the extremes of travel.    If it tightens up before you get there that is some wear.      Check the screw backlash at mid table and again at full left right travel.    Any difference is screw wear.   
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Online Jo

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Re: Advice on buying a vertical mill.
« Reply #11 on: February 18, 2018, 09:17:11 AM »
Presumably buying from a reputable dealer like G & M gives some sort of assurance though.

Even reputable dealers pick up the odd dud one. What ever you consider look and if possible try before you buy.

I have been lucky with my second hand purchases as I have taken my supplier Eric (Muddled Engineer) with me: Eric used to help out a number of dealers by repairing machine tools so always knew when there was a real bargain to be had like my Mr Silky and Tgs  8) I think the last machine he brought was a low milage second hand Ajax universal Mill from Warco for £800  ::)

Jo

P.S Eric tells me the machines at G&M came from Southampton University  ;)
« Last Edit: February 18, 2018, 12:10:38 PM by Jo »
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Online Alyn Foundry

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Re: Advice on buying a vertical mill.
« Reply #12 on: February 18, 2018, 11:51:24 AM »
Good morning John.

Your first post said it all, we all push our machines to the limit of their capabilities from time to time. My engineering mentor, Alex always recommended that you buy the biggest machines that both your workshop and pocket could accommodate. What’ll do a lot will do a little he used to say.

My main milling machine is a 2 ton Denbigh universal, an antique, but she can remove metal like it’s going out of fashion! The cuts I can take would stall most machines.  It came with all the extras, I even have a slotting head, very useful. Way back I even managed to machine a pair of 2 foot diameter flywheels by fitting a faceplate to the horizontal spindle nose. The knee depth being large allowed me to bring the table forward and upward to mount a toolpost.

You can’t beat the versatility of a Turret mill but it’s a case of “ horses for courses “ it’ll really depend upon what you want to do with it.

Cheers Graham.

Offline Manorfarmdenton

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Re: Advice on buying a vertical mill.
« Reply #13 on: February 18, 2018, 05:33:07 PM »
Hello Graham,

I'm afraid I'm guilty of occasionally pushing my machines well beyond the limit of their capabilities.  That's probably a lot of their trouble!  My old mill was made in 1943, the year I was born, and when I bought it about 26 years ago it had been used for planing cylinder heads in a local car garage.  I've done things like tidying up flame-cut circles of 12mm plate too big to go in the lathe, using a rotary table and end mill.  The interrupted cut presumably wasn't good for the quill, so I mustn't whinge if it protests by wobbling sometimes!  Thinking about it, the same goes for the Bantam - I've hung a 200mm chuck on it because the standard 150mm one wasn't big enough, and sometimes had chunks of round in it which I could hardly lift.

Steamer - out of interest I'm about to go and do what you suggested.  I'll report back  :)

John.
John Fearnley

Offline Manorfarmdenton

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Re: Advice on buying a vertical mill.
« Reply #14 on: February 18, 2018, 06:00:07 PM »
Results of test! 
The backlash in the X axis leadscrew is about 1/4 turn.  This isn't significant to the DRO I fitted, but can cause the tool to grab if the table jumps.
I semi-tightened the clamp screw with the table in the centre and I couldn't traverse to either end. It went tight about 3/4 of the way along.
I set a DTI against the collet chuck and by pushing and pulling by hand could move the spindle about 20 thou.  I feel slightly silly about that as I haven't checked the pre-load yet, as Graham suggested.  Also, when I run the old girl at 1700 rpm - the lowest of the 'high' range speeds and I very seldom use the higher ones - the head occasionally emits what I can only describe as a loud cracking sound.  Don't know what it is but it has occurred off and on for years now, so I don't think anything is about to disintegrate!  It doesn't do much for my confidence though!

Oh, and did I mention it was made in 1943..... :D
John Fearnley

 

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