Author Topic: Advice on buying a vertical mill.  (Read 7701 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.
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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.

Offline 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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Offline 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.

Offline steamer

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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.
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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.
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Offline 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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Offline 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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Offline 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.
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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
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Offline steamer

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Re: Advice on buying a vertical mill.
« Reply #15 on: February 18, 2018, 06:08:03 PM »
Well if you're just snagging flame cut plates it's perfect!... Now if your trying to keep flat square to a  fly's but...well....not so much...
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Offline Manorfarmdenton

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Re: Advice on buying a vertical mill.
« Reply #16 on: February 18, 2018, 10:06:29 PM »
Exactly!  I'll keep the old mill for rough jobs - a thou or two is neither here nor there when making centres for tractor front wheels - and use one with a bit more accuracy for fine work.

John.
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Offline john mills

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Re: Advice on buying a vertical mill.
« Reply #17 on: February 19, 2018, 10:01:38 AM »
the cracking sounds could be the spindle bearings have gone past the no preload to completely collapse soon on site recently (,i do labour hire work)  the turret mill made crunching noises as it lost drive to the spindle .several times.
when dismantled the cages had disappeared the balls were all around one side .the bearing were of very light ,the lightest section angular contacts .nothing like the bearings in the mills i am used to using .

Offline Manorfarmdenton

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Re: Advice on buying a vertical mill.
« Reply #18 on: February 19, 2018, 11:42:18 AM »
John - I wouldn't be a bit surprised if that's exactly what has happened.  I've been having visions of collapsed cages!  Trouble is one of my (no doubt many!) failings is to keep using something until it packs up on me.  An unidentifiable engine noise becomes a tap, the tap becomes a knock, and the next thing you know you're in the middle of a field looking at an engine block with a connecting rod sticking out of it.  It happens, and not just to me!  It's not quite as daft as it sounds as the driver of a big old crawler probably can't hear the engine because the transmission is making so much noise.
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Offline Mcgyver

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Re: Advice on buying a vertical mill.
« Reply #19 on: February 19, 2018, 02:05:49 PM »
Here are my thoughts on it.

1) get out see them.  Dealers, locals classifieds etc- look in the eyes seller as well as the machine.  You learn when you've seen a bunch and will develope a sense of what is a nice one.

2) avoid ebay.  Buying a machine sight unseen is a mess waiting to happen imo.  This should be the last recourse reserved for those machine tool desert dwellers.

3) Operationally backlash does not matter.  If its an acme screw, there has to be some (clearance) or the thread wouldn't work.  If there is some, there is to much for climb milling....except extremely light climb milling using the table's inertia in which case again how much backslash there is doesn't matter. 

4) Where backlash does matter is an indication of overall wear.  A machine that was used heavily and not regularly lubricated with have more backlash.  Backlash is wear of the feedscrew and or nut and is usually localized so will affect long distant measurement.  That's where the value of a DRO comes in, that and general convenience.

5) I have reconditioned several machine tools, ground up scraping, and can describe exactly how to quantity wear through a complete survey.  Problem is the machine has to be in parts and it would take a day or two spread out all over the place.  In other words properly quantifying wear is not really possible at the vendors site.  Some basic tests, move things end to end, if cranking the wheel is consistent and they dovetail is not getting tighter, there is little wear....or the gibs have been loosened - check for that standing at the end of the table and see if you can move the table side to side a bit 

6) instead of quantifying wear, we look for it by proxy.  Does it look likes its had a long hard life, paint all chipped (or the worst of all, freshly painted at a dealer), when the saddle is moved to its extent, what do the ways look like?  are they dry?  And so forth.  This is where backlash does matter - as in indicator of wear.

7) What does it come with?  Wait until you get a really well accessorized one, ideally collets, end mill holders, power feed, drill chuck, RT, dividing head and vise.  maybe even a DRO, but imo that's the least important.  Loaded, they sell for more, but that increase is a tiny fraction of what it'll cost to acquire it all

8)  Warm the bearings up then take it up to speed, run the quill up and down.  everything quiet?  make some cuts if possible, load it a bit....still good?  Spindle bearing replacement isn't the end of the world, but putting in the good P4's is a significant add cost.  If its not under power, negotiate downward and assume you have to cover the cost of say bearings....hopefully not, but not being under power means the vendor should have lower expectations

Not that point 8 is particularly cool but in this smilie infested world, that's what you get with the numeral 8 residing next to the bracket

9)  There are lots and lots of vertical mills, a great of which are a little more robust than the bridgeport.  Don't limit the search to the one name

10) but a tenths indicator on the spindle.  Measure not just TIR, but apply some pressure to the spindle and make sure there is no movement.  This recently saved me from dog being sold by someone who is known as a really unsavory vendor.   Also inspect the taper, looking for obvious abuses.

11) if you haven't already, consider moving up to a 3P machine.  Lots of ways, now easy with VFD's, to get the 3P and it opens up the market substantially as to what is available

12) finally, patience.  The old cliche is so true for our stuff - you want it hi quality, low price and fast?  pick two
« Last Edit: February 19, 2018, 02:28:59 PM by Mcgyver »

Offline Manorfarmdenton

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Re: Advice on buying a vertical mill.
« Reply #20 on: February 19, 2018, 02:49:41 PM »
Mcgyver - useful tips, thanks. 

The main reason I've looked at Bridgeports is because my friend has one.  I'd possibly prefer a slightly more rigid method of toolholding though?  My old girl is MT3, almost certainly with a worn socket, the Bridgeports are R8 I think, but Int. 40 would be even more rigid wouldn't it?  I've seen some of them at affordable prices.

For a novice like me DRO is important, but presumably can always be added, and a 2-axis one doesn't cost the earth.

Taking a DTI to test spindle movement is easy enough.  Good suggestion.

No I haven't considered 3P.  I might if I knew what it was though  :)  I had to look up VFD too.  One issue I have is that, being in the middle of nowhere I haven't got 3-phase so have to use a Transwave converter for the Bantam.  I know the output isn't quite like 3-phase but ordinary motors don't seem to mind.  Not sure about VFD though?   The mill I converted to 1-phase when the old 3-phase motor started blowing the trip!

John.
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Offline Mcgyver

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Re: Advice on buying a vertical mill.
« Reply #21 on: February 19, 2018, 03:12:28 PM »
3P =  3 phase power.   Is your transwave a static or rotary converter?  I used a static for years, it works, but does under perform other options.  Currently I have a 10hp rpc I built, some machines run on 240 3P for others I bump it up to 600V (my garage is a next of conduit!).  RPC (rotary) still the way to go if you have lots of machines because you really need i inverter (VFD) per machine, but if only one machine, go VFD

You can run 1ph into a VFD and get output to turn a 3P motor, this is extremely common now.  All the VFD does is rectify the incoming power onto a DC bus.....how it gets to that DC bus doesn't much matter.  You DO have to overate as you are only using two of the diodes for rectification and there is going to be more ripple.  Many vfd's are intended for this with 1P in specs.  The only downside is they get pricey as the HP goes up and you have to over rate them.  The plus side is silence, no drone of the RPC in the corner.

As for 40, yes, it is so much better.  I've an R8 XLO and that machine also came in 40.  As I see them come up i've been tempted a few times to upgrade but its a lot of machinery moving and I have a lot of R8 tooling....but given the choice between the two, 40 the clear winner.  I've an Elliot horizontal that is a 40, it will go through anything.

DRO's are a nice convenience to have, after holding out for 25 years, I added one 2 years ago and like it a lot.  But really, the only practical problem they solve is feed screw error over a distance (which you could overcome and I've done so with tool maker buttons and gauge blocks).  Other than that, long distance error thing, backlash doesn't matter much and everything can be done with the dials.  My point is they are a nice convenience but it would a lower priority for me in looking for a machine given 1) they are mostly a convenience not a necessity and 2) they can always be added.  If it had it great, but I'd be a lot more focused on the machine's condition and tooling.
« Last Edit: February 19, 2018, 03:35:37 PM by Mcgyver »

Offline Manorfarmdenton

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Re: Advice on buying a vertical mill.
« Reply #22 on: February 19, 2018, 04:51:35 PM »
Of course I know what 3P is - typing finger was in gear but brain was in neutral  :)  Sorry.

My Transwave is static.  I think it runs up to 7.5hp.  It has about 10 (from memory) settings and I use #1 for my small 3P bench drill and #6 for the Colchester Bantam lathe.  I think the old mill used to like #3 before I converted it to 1P.  The only thing I have had that it wouldn't run was a 3P surface grinder I bought a while back.  For some reason the grinder seemed to have more wires going in than the Transwave had coming out!  I'm no electrician but have asked a couple of acquaintances that supposedly understand things like that, but they couldn't make it work either.  I know it was going before I moved it though.

I have a 3P supply from it running round the workshop in metal trunking, so it isn't too difficult to connect multiple machines.  I just need to alter the switch until the motor in question runs nicely - e.g. the lathe won't run at all on #1 but the drill motor is very noisy if I forget to switch back from #6.

John.
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Offline Mcgyver

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Re: Advice on buying a vertical mill.
« Reply #23 on: February 19, 2018, 05:46:05 PM »
The only thing I have had that it wouldn't run was a 3P surface grinder I bought a while back. 

your's sounds like perhaps a different issue (the omg there's left over wires issue), but I've been told static phase converters do a poor job on free wheeling things; i.e surface grinder, table saw etc.  It needs a bit of a load on it like a machine's gearbox provides, apparently.  One dodge is to get some other machines running first, their motors start to act like the idler in a RPC.  I haven't tried it, built an RPC instead.

Offline Manorfarmdenton

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Re: Advice on buying a vertical mill.
« Reply #24 on: February 19, 2018, 08:26:58 PM »
Interesting.  I know the 'spare wires' issue isn't relevant, but in the case of the Bantam, the coolant pump won't run on its own.  You have to start the lathe motor first, then switch on the coolant pump.  That's because the converter can't cope with the small-power motor on its own though.

Incidentally I tried using the wires coming out of the surface grinder in various combinations, with some quite spectacular results.  Luckily the RCD and/or MCB in the main fusebox prevented major damage, apart from to my nerves!

John.
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Offline Manorfarmdenton

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Re: Advice on buying a vertical mill.
« Reply #25 on: March 10, 2018, 11:27:38 PM »
I'm considering this, subject to inspection.

http://www.gandmtools.co.uk/shop/hartford-5kv3-variable-speed-turret-mill-dro-3ph-80204721

It looks pretty substantial in the photo and the 40 INT tooling should be more rigid than R8 or my existing 3MT shouldn't it?  It also seems to be better value than a Bridgeport, probably because its not as popular a make?  I've tried to ring G and M but haven't spoken to them yet.  Any comments?  It probably won't fit in the space I had in mind but I can find a home for it!

John.
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Offline Jo

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Re: Advice on buying a vertical mill.
« Reply #26 on: March 11, 2018, 08:06:30 AM »
  I've tried to ring G and M but haven't spoken to them yet.  Any comments?  It probably won't fit in the space I had in mind but I can find a home for it!

That was the one Eric wanted to buy but I had to talk him out of it as he spends more time buying and selling machine tools that are "better than the one he already has" than making swarf  :ShakeHead: When you get into your 70's you need to get on and make all those models you waited all your life to build  :D

Jo
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Offline Jasonb

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Re: Advice on buying a vertical mill.
« Reply #27 on: March 11, 2018, 08:19:28 AM »
But he has also bought ones that he thought were better than he had only to find hidden problems once he got them home :-[

I would do a bit of research on that make as if you do need spares at least there are a few more options about for Bridgeports.

Offline john mills

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Re: Advice on buying a vertical mill.
« Reply #28 on: March 11, 2018, 08:47:06 AM »
int40 is a much more robust spindle taper and much more desirable have used them at work where R8 and number  3 morse would be of no use at all.
CNC machining centres often use similar BT 40 i have used BT45 which is even better. But machines  need  a
spindle and bearings bigenough for enough metal for the taper to fit. 

Offline Jo

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Re: Advice on buying a vertical mill.
« Reply #29 on: March 11, 2018, 09:01:10 AM »
But he has also bought ones that he thought were better than he had only to find hidden problems once he got them home :-[

I would do a bit of research on that make as if you do need spares at least there are a few more options about for Bridgeports.

If you mean the Karradi he knew that was a dog when he gave them the £500 for it delivered... But he thought a universal mill with 3 axis power feed and quill feed and shaping head was worth a punt if he could fix it ... Sometimes paying scrap money for a machine means they need a bit of work that one beat even him  ::)

All of those big machines at G&M came from Southampton University and have had little use.

Jo
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Offline Manorfarmdenton

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Re: Advice on buying a vertical mill.
« Reply #30 on: March 11, 2018, 11:08:26 AM »
I'll use it to do 'full sized' stuff as well as model engineering, which is what I found attractive about the 40 INT  spindle nose.  My poor old 3 MT boring head jumps about when I bore a 4" hole.

Power feed on the X axis is a requirement but I don't mind so much about the other two.  DRO is a necessity too but not important on the quill, although I could fit a cheapy from eBay if I thought it necessary.

I agree about spares Jason, but I'm not going to be using it in an industrial situation so don't think they are a huge consideration are they?  It looks hugely chunky compared with the Bridgeports on offer for a lot more money, does it not?  Who sold it originally and how old is it?

I expect I'll get a reply from G and M tomorrow and will be interested to hear what they say about it.  I've looked up Hartford 5KV3 on Google but can't see any full specs including dates when it was available and dimensions.
John Fearnley

Offline Alyn Foundry

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Re: Advice on buying a vertical mill.
« Reply #31 on: March 11, 2018, 11:11:06 AM »
Good morning John.

It's a nice machine. Far Eastern, and " generic " spares readily available. It's virtually the same machine I used to use at Chester UK.

As I see it your problem will be the motor. At 5 KW it'll be right at the top end of your static phase converter. I'm also pretty sure the motor doesn't have the " Star point " available to use a VFD.

The " vari speed " heads are marvellous, two speed mechanical with an infinitely variable belt drive over the low and high setting.

They are very robust machines.

Cheers Graham.

Offline Manorfarmdenton

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Re: Advice on buying a vertical mill.
« Reply #32 on: March 11, 2018, 11:43:23 AM »
Morning Graham!

I should have told you the casting arrived safely!  I'm part-way through machining it.

Thanks for the input and reassurance about spares.  My Transwave converter is 7.5 KVA capacity and powers the Bantam with its 4 HP motor on no5 of 8 output settings - I just checked to make sure - so I shouldn't have a problem?  Its a pain not having 3PH - we have 2 phases coming onto the property at 440V or whatever and the big welder , being an auto-transformer, uses the higher voltage.  I enquired about having 3PH brought in but apparently the local transformer would have to be changed and the cost to us several years ago would have been somewhere in the region of £10K.

John.
John Fearnley

Offline Alyn Foundry

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Re: Advice on buying a vertical mill.
« Reply #33 on: March 11, 2018, 03:19:54 PM »
Hi John.

Glad to read the OEM part arrived safely.  :)

Two phases, that's unusual but, I'm pretty sure there are VFD's that can convert a 415 two phase input into a 3 phase ( 415 volt between phases ) output, advice from a supplier should be sought.

The beauty of modern VFD's is the efficiency, up to 98% against 50% with static phase converters.

With the milling machine in question, a 50 HZ output is all that's required as the machine itself has variable speed with the belt.

Cheers Graham.

Offline Manorfarmdenton

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Re: Advice on buying a vertical mill.
« Reply #34 on: March 11, 2018, 04:21:27 PM »
I'll speak to someone Graham.  I don't know much about our supply apart from the fact that the previous owner (a farmer who had been here since it was put in) called it split phase when I moved here in the 60s.  There were one or two enormous (for their HP) electric motors driving barn equipment and a water pump, and half the domestic supply is on one phase and the other half on the other to share the load.
Apart from the proposed mill, we have a large 3PH hydraulic press that we were given but have never used, so its worth finding out a bit more.

Carb casting is coming along.  Don't you just love machining cast iron - its so satisfying!

John.
John Fearnley

Offline Tennessee Whiskey

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Re: Advice on buying a vertical mill.
« Reply #35 on: March 12, 2018, 09:20:05 AM »
John, don’t know if something like this available on your side of the pond, but, I use one on my Bridgeport clone and Monarch 10ee and have had no complaints or problems.

https://www.americanrotary.com

Cletus

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Re: Advice on buying a vertical mill.
« Reply #36 on: March 12, 2018, 11:29:17 AM »
Thanks for that Cletus.  I'll investigate whether they are available over here, but if they aren't there are several makes of rotary ones that are.  I'd have to take advice on which I would need - which model do you have?  Reading the AR Series specs, presumably I'd need one that will start 5HP on an easy start as a mill running light wouldn't be a hard one?  Like that the 7.5 would do.  I'm also bearing in mind that it wouldn't be in constant use as in an industrial situation.  Some weeks it might work most days for an hour or two and other weeks not at all.  I'll also ring Transwave and ask what my present one is capable of.

John.
John Fearnley

Offline Manorfarmdenton

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Re: Advice on buying a vertical mill.
« Reply #37 on: September 27, 2018, 09:43:02 PM »
Having been sidetracked for months, I'm finally back to making a decision about the mill!  Today I've been to Leicester and then up into Staffs to look at some used turret mills.  The choice seems to be between  a very nice, little used one with R8 tooling, 1998 vintage, and a very similar but not quite so pristine 1998 Excel machine with 40 Int spindle nose.  Both have 2 axis DROs and variable speed drive and are around £4000 plus vat delivered.  The R8 machine has power lift to the knee and its slides and table are absolutely pristine, the 40 Int one appears to be very nice but isn't quite as pristine, as I say, and the price is £300ish more delivered.
Both machines seem very hefty compared with the old lady I've been using, but is there any big advantage in having the 40 Int tooling?  Is it much more rigid than R8?  Does the little pin break so the R8 drive isn't positive - eg when using a boring head on biggish holes?  I have used mine on occasion to bore a 100mm hole in steel, and that was with a boring head with 3MT shank.
I've said I'll make a decision over the weekend, but I'm totally confused, so any advice will be gratefully accepted! 
Thanks in advance, John.
John Fearnley

Offline jadge

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Re: Advice on buying a vertical mill.
« Reply #38 on: September 27, 2018, 10:31:52 PM »
In theory INT40 will be much more rigid than R8. But it depends upon the rest of the mill. My Bridgeport (R8) is versatile but not especially rigid. I doubt it would be much better with an INT40 taper. On the other hand my horizontal mill, with INT40, makes a brick built outhouse look flimsy and can make use of the INT40 taper. It didn't even cough taking 2mm depth of cut and 8 thou per rev feed in cast iron swinging a flycutter at 9" diameter.

By the way the little screw in the R8 taper isn't a drive pin; it's purely to stop the collet rotating when tightening the drawbar. The taper transfers power solely by friction. On both my R8 taper mills they're broken and I don't miss them in the slightest. I've bored 3.5" holes in steel on the Bridgeport without a problem.

Andrew

Offline Jo

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Re: Advice on buying a vertical mill.
« Reply #39 on: September 28, 2018, 07:51:13 AM »
The other thing to bear in mind is the availability of tooling: R8 is hard to come by, in comparison 40 Int is much easier.

Both of my larger mills are set up for using 30 Int tooling in the early days that was like Hocking horse do-das to find but thanks to CNC (and Flea bay) that is much easier to find these days.

Jo

P.S. 40 to 30 Int converters are available  ;)
Enjoyment is more important than achievement.

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Re: Advice on buying a vertical mill.
« Reply #40 on: September 28, 2018, 07:18:16 PM »
Thanks Jo and jadge.  Interesting re the screw /pin in the R8 socket.  They were missing in most of the mills I looked at.  I hadn't thought much about availability of tooling but did ask for an ER32 collet chuck to be thrown in and both vendors agreed to supply new ones - I have a full set of ER32 collets that I use with my old 3MT mill.  I think I'd also get holders for my Clarkson imperial and metric collets in either deal.
As regards rigidity, the two machines are very similar in build apart from the spindle, but the R8 machine is 3hp while the 40 Int one is 5HP.  Presumably that's significant as the 40 Int socket is capable of transmitting higher torque?  How much that matters I'm not sure, as jadge says R8 is capable of boring a 3.5" hole and I've done a 100mm one with 3MT?

Another machine I've been offered is a Cincinatti with 40Int spindle, very rigid but it looks as if its seen more use.  It would be about the same money but would have a new 2 axis dro and an additional slotting head.  It doesn't have power to y axis or knee, but that isn't the end of the world.  I don't know - I'm still indecisive!  John.
John Fearnley

 

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