Bridgeport Manual to CNC conversion...

CSMIO unit on order, motors on order, ball-screws ordered, wallet crying :(

Panel controls...

With the Bridgeport you have to run in reverse when in low range, is there a way to have this done in Mach3 or will it still be a Hi/Low selector switch on the panel?

The VFD for main spindle, with the vari-speed mechanical system I'm not sure if i should try using the vfd as variable or leave it fixed at 50Hz, the top speed is limited to 3500rpm absolute max as it tends to wreck the spindle bearings above that and low down it probably would not have the torque needed, so stick with mechanical ?

Main spindle on/off manual control - would these buttons control Mach3 or would they control the vfd directly?

Just looking for ideas here.

Food for thought...

While waiting for the screws & motors to arrive, should I strip her down to the bones and clean / paint the old girl ;)

Would take a bit of effort as it would need space clearing to get the engine hoist in to lift the head, ram, collar, bed and knee off.

Could be useful as it would allow me to check for worn out bits, split lube pipes etc.. Would also make the build and wiring a cleaner job by getting rid of the grime and muck.

Hmm....

Quote:

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Originally Posted by Davek0974

Food for thought...

While waiting for the screws & motors to arrive, should I strip her down to the bones and clean / paint the old girl ;)

Would take a bit of effort as it would need space clearing to get the engine hoist in to lift the head, ram, collar, bed and knee off.

Could be useful as it would allow me to check for worn out bits, split lube pipes etc.. Would also make the build and wiring a cleaner job by getting rid of the grime and muck.

Hmm....

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Yes and get the knee saddle and table reground and turcited. Speak to slideway services, they quoted me by far the best price

Looking at replacing the mechanical speed control and back-gear with an AC servo motor, something like this...

http://www.aliexpress.com/store/prod...760988112.html

Should give full power across the board I think, also no loss in the drive belt and no changing gear for low speeds.

Bingo! Much better than your VFD approach. Have a look at the ones rated for spindle usage. They will work better at higher rpms. i have specced a GSK one on my new machine. Now you do not really need to have it go full servo unless you want to do rigid tapping.

Quote:

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Originally Posted by komatias

Bingo! Much better than your VFD approach. Have a look at the ones rated for spindle usage. They will work better at higher rpms.

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I agree George the AC Inverter Spindle Motors are the correct approach but they are still often controlled via VFD or Inverter. My Semco Mill as 5Kw Inverter Spindle Motor and that is controlled via ABB inverter.
Difference between ordinery motor being will spin to 7500rpm and still provides lots of torque.

The latest AC Asynchronous Servo Spindle Motors are great but would be completely OTT for Old BP like this and cost more than the whole setup.

Personaly for the price of cheap VFD I'd use what you have. If the BP motor is upto it and you have tapping head don't see the point.?
Edit: I might be tempted to remove the Variable drive setup and go direct drive but wouldn't bother with Servo unless need the Indexing etc it provides. Even then this is possible to lower degree by fitting an encoder to vfd provided it supports this option.

Attachment 18486

Hmm, got the head apart now, to refit it will need new bushes in the sheaves plus a new drive belt, probably £100 odd? I already have a VFD on it but only use it as a converter at 50Hz.

OR

I can pull the lot, fit a 1.8kw AC servo rated to 3000rpm, 1:1 poly-v drive and along with the back-gear if ever needed would give me full control from G-code - total cost about £400

So we are looking at about £300 difference for luxury servo drive??

What to do ;)

Quote:

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Originally Posted by JAZZCNC

Personaly for the price of cheap VFD I'd use what you have. If the BP motor is upto it and you have tapping head don't see the point.?
Edit: I might be tempted to remove the Variable drive setup and go direct drive but wouldn't bother with Servo unless need the Indexing etc it provides. Even then this is possible to lower degree by fitting an encoder to vfd provided it supports this option.

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Davek,

see what the man says above. no point in going servo on a bridgeport.

Either way, do look at getting a power drawbar and some quickchange TTS type tooling

Quote:

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Originally Posted by Davek0974

I can pull the lot, fit a 1.8kw AC servo rated to 3000rpm, 1:1 poly-v drive and along with the back-gear if ever needed would give me full control from G-code - total cost about £400

So we are looking at about £300 difference for luxury servo drive??

What to do ;)

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Thats £300 extra for what.? Ridgid tapping that you don't need.! Indexed postioning you don't need because no ATC.!
Controller will give you every thing you need regards speed control etc from G-code using VFD just like it would if Servo so don't see the point.
Only advantage I see is the indexing and possibly extra torque at lower speeds, but you have back gear so not problem.

Save the Dosh and spend it else where.!

Yep, it was a nice thought but had a good think over dinner and using the existing motor and VFD is the sensible option. As said, rigid tapping is not needed and using the variable mechanical drive with the VFD as well will give full spread of speed and torque from 40 to 3000rpm if using back-gear or 400 to 3000rpm in high alone. My tweaked macro will tell me where the mechanical dial needs to be so problem really.

It was a nice thought but a luxury and cash will be needed for fitting out the cabinet etc, when i find one big enough.

CSMIO, servo motors and drives arrived a minute ago, all looks very heavy-duty indeed, just ordered a DB25 break-out block for the MPG unit and one of the neat little power divider blocks from CS-Labs :)

Got the mill head stripped, paint on order, removed all the surplus gears and junk from the head.

Wondering about doing the neat Z axis fit where the ball-screw takes the place of the feed-stop screw and is a 1605 unit OR doing the more common fit where the ball-screw sits in front of the original feed-stop screw position???

The only downside I see with the first option is that the pulley sits at the bottom of the screw right in front of the spindle nose.

I will send you a photo of my setup later on. I have made parts to allow me to use the manual quill with the removal of a single screw.

Also look on CNCzone for SCzEngrgGroup's conversion of the bridgy.

Have motion on the test motor now :)

Needs tuning i am told but there does not seem to be a tuning option in the drive menu??

I did an auto-tune in CSMIO but that only goes so far, even the manual tells me it needs to have the drive velocity tuned in the driver before auto-tuning or it will fail.

Sounds like a question for Jazz, write that you've decided to use a 6560 and he will appear:triumphant:

It seems the drive is pre-set when enter the motor code number so no tuning in the amp.

Have finally got the head apart on the mill - a tiny broken shaft was holding me up - an absolute bugger to get out.

Attachment 18494

Attachment 18495

Now thats off it should move a bit more rapidly. The plan is to do a complete strip, wire-brush the poor repaint job it has off then sand and repaint in "Bridgeport Grey" engine enamel and reassemble to a bare machine then fit the CNC conversion.

The DRO and Original, working power-feeds will be sold off to raise funds.

Space is the biggest problem, will probably have to erect a shelter and do most of the prep in the garden.

Thoughts over coffee - Limitations of the system?

When i was building the large scale traction engines, everything was made with a tolerance of only 0.1mm or better - easily obtainable on a hand controlled Bridgeport with a three digit DRO. It really was not needed to go tighter on these engines and many say that if too tight they never worked properly due to expansion when running etc.

Anyway, the third digit on the DRO was pointless as you could never set that precision by hand and merely looking at the mill out of the corner of your eye made it wobble more than that!

So, now (when done) I will have ball-screws and servo's with Mach3 acting as my DRO display - this is all running on my bench very nicely now.

But - the encoder/motor is connected to the screw via a toothed belt - surely this must introduce an error possibility, especially with a 100kg sitting on the bed??

My main point here is - If i want to use the mill manually, say to drill some holes without cam-ing the job, I can put Mach into reset, this drops out the servo motors and i can spin the handles like before and Mach tracks the position on screen - I am hoping here that this is a workable situation with decent accuracy when positioned manually??

Quote:

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Originally Posted by komatias

Yes and get the knee saddle and table reground and turcited. Speak to slideway services, they quoted me by far the best price

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At £950 + VAT + transport there and back this will have to wait i'm afraid. I have chrome ways so that put the price up as well.

Quote:

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Originally Posted by lucan07

Sounds like a question for Jazz, write that you've decided to use a 6560 and he will appear:triumphant:

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No I won't .!! . . . . Because I already told him via Private bongo's.:monkey:

Quote:

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Originally Posted by Davek0974

But - the encoder/motor is connected to the screw via a toothed belt - surely this must introduce an error possibility, especially with a 100kg sitting on the bed??

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Not really if the belts are tensioned correctly and decent quality. Lots of very expensive VMC have belts on the screws.

Regards Manual operation then it will Display position just like Manual DRO's would.

Was playing around with PID tuning today, reading the manual on how to do it manually (ooh-err) It was not happy and no amount of fiddling got it better, long positioning time, not sitting at position etc. That was until i stuck my finger on the end of the shaft and gave it a tiny amount of resistance - instant improvement rapid stopping on position etc. Lesson learnt, seems unloaded motors don't like tuning ;)

I have ramped it up to 3000rpm, been deliberately messing about with rapids for several metres each way plus millimetres each way, then put mach into reset and jerked the motor around, reset and did a go-to-zero and the damn thing snapped straight back to my zero mark - I was most impressed with this feat ;)

JAZZ - how did you wire the enable line to the drive - there is a signal mis-match here as CSMIO puts out 24v but the drive needs to be pulled low - I stuck a relay in which works but....

Also, what size fuse would be good for a drive and 750W servo?? Thinking 5A slow-blow?

Quote:

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Originally Posted by Davek0974

JAZZ - how did you wire the enable line to the drive - there is a signal mis-match here as CSMIO puts out 24v but the drive needs to be pulled low - I stuck a relay in which works but....

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I do it with a relay tied to the HV option on IP-A that enables all the drives.

Thanks, if it really is relays then thats fine, I have that working on the bench setup, just wondering if that was the only option here :)

Ok, where did I slip up...

Previously had the motor tuning set as book, 2000 steps per (10,000 / 5mm pitch)

When I fit this on the machine it will be at 2:1 ratio so i set steps per to 4000 (10,000 * 2 / 5mm pitch) and set velocity to 7500 (3000rpm / 2 * 5mm pitch) acceleration is at 750mm/s/s

Works ok in jog mode, works ok in code mode at speeds up to 7500mm/min

If i do a "Goto zero" it runs for a while then stops with ePid fault.

It also allows me to set feed higher than it can handle and then goes into ePid fault.

Is there a reason here?

Ok, found it - it seems it does not like running right at the limit of max speed - if kept just below max it all works perfect.


If I set the max at 7500 and command a feed at 7500 it faults, if I set 7400 it works perfectly in all modes.

Won't get t hat high in real life as the bed is not really big enough i think for a 7500mm rapid ;)

Just to throw a spanner in the works may be completely irrelevant but on my travels today saw a bridgeport (couldn't tell you the model) converted to CNC, that used original and a 24k spindle slightly different setup to your plan.

The 24k spindle was mounted literally beneath the original in a frame so when changing between spinles he just had a Z offset to consider but apparently with Knee or second Z thats not a problem, frame actually locked into a collet then connected to frame, his spindle was shorter than mine and he lost a fair bit of Z travel but this still left a good amount of travel on Z for what he used the 24k for.

Just thought I would share unfortunately I was out on the road bike (lycra man) to escape idiots for a while so no phonewith me to grab a picture.

Should these collars just slide off, it feels like they are hitting a hard stop?

Attachment 18520Attachment 18521

Probably surplus on a CNC machine anyway but don't know yet.

Just a thought, have you tried tapping them round had similar collars in a different setting but they were threaded.

No, one of them slides about 3mm and then stops, the other is stuck fast

Can't go much further ;)

Attachment 18522
Attachment 18523

Stripped most of the poor paint job off now, will be sanding and painting this weekend, not filling the dents in as it's a machine not decoration ;)

Now for the spare parts :(

The knee lift-screw bearing is dead, it looks like a 3306-2RS Double row angular contact 2 rubber shield item - 30mm ID, 72mm OD, 30mm W

Can anyone confirm that please?

Also is there a good source for the tubes and fittings for the lube system in the UK, might replace the lot as it looks like some of the points on the knee lift ways were doing nothing, luckily i always backed up with the oil can;)

Off subject just making sure you have this came across it looking for something else looks interesting

http://neme-s.org/Shaper%20Books/bri...%20Rebuild.pdf

I got replacement Bijur metering units for my mill from Lubetec. They do have a web shop, but it's just a generic skinned airline/pneumatics one used by lots of similar suppliers, and doesn't contain any of the lubrication stuff.

They do however have their own catalogue online, which contains all the centralised lubrication stuff.

I did consider the Arc Euro parts, however the threads were wrong and the genuine Bijur ones weren't that much more expensive. Just checked and they were £5.54+VAT each a few years ago, so not worth the hassle of retapping threads and changing fittings.

You'll need to get the flow rate of the existing metering units, as well as the thread/style/direction of flow if you need new ones.
I removed all the metering units from my mill, connected them up, and then left the lube system running overnight (it's an electric motorised one designed to lube every few hours). Any that were still dry in the morning, I replaced as they're pretty much impossible to clean properly once gummed up, and a few metering units is far cheaper than the potential damage from lack of lube.
One trick I did use, was to fill the system with ATF fluid and leave it running for a day. You can then check that all the slides have a nice coating of red oil, which tells you the system is working and getting oil to where it should.

For replacement pipe/fittings, I just used whoever could supply them. My mill originally had aluminium distribution pipe, which had corroded where it had been sitting in coolant, so I replaced it with the same sized copper pipe.

Thanks I'll have to test them all first then.

The plumbing is all nylon so that should be cheap enough with some olives.

Mine is a manual pull-pump by interlube.

Looking better...

Attachment 18524

Got the knee painted too.

Hit a block now - turns out the knee-lift screw bearing is dead, got the deadly silver paste coming out of it and feels like a bag of nuts. Will have to order one from somewhere but cant reassemble until i get it :(

Got most of the big stuff stripped , sanded and painted now. Started putting a few little bits back on but cant do much until i get the new knee lift bearing.

Found an issue with old lube system - this is the feed to the saddle...
Attachment 18527
Olive was cocked and tube crimped, probably wrong size olive for the pipe :(

Moving on....

Motor mount plates for X & Y axes.

Is it better to hang the plates from the four bracket mount screws or the three bearing retainer screws?

Attachment 18528

Using the four screws would mean a much larger lump of metal is needed to span the width, I won't be refitting the dials so using the three mount screws probably won't affect anything.

Any thoughts?

Go off the plate:


https://lh3.googleusercontent.com/-u...mounts%2B-%2B4
https://lh3.googleusercontent.com/-R...mounts%2B-%2B5


I made a spacer and clamped it all there.

My Y axis one looks like this:

https://lh3.googleusercontent.com/-a...mounts%2B-%2B3
https://lh3.googleusercontent.com/-v...mounts%2B-%2B7


I bought proper angular high spec contact bearings for the screws (+£250) and some very fancy face locking lock nuts from Germany.

Very nice :)

Have you any more pics, looking for ideas on homing/limit switches etc

I had not thought of putting the Y motor to the rear, all the builds i have seen have it hanging down low beneath the handle, it will have to stick out though as my motor is too long to tuck under.

Dave, I have mounted my limits off of the newall DRO scales but not happy with them. Going to be printing some parts shortly to fix the issues and will post.

Ok, I am only using the Mach DRO's - my Sino DRO kit will be sold to raise funds, can't really see the need to have two DRO systems.

Yes, with the CSMio you can get away from the extra DRO. I have it becuase I am using steppers and a smoothstepper but also have a very cunning plan there too.

What kind of switches are you planning on using?