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Topics - EJParrott

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1
General Mach Discussion / Screen size
« on: July 15, 2013, 03:32:17 PM »
I've had a chance of plan...  I was originally going to buy a laptop for running my bridgeport, but I've decided now to use my old desktop PC.  It saves me money for a while, and it's a known quantity...I could buy a cheap laptop from a well known auction site but it'd be an unknown - and I've been there before.

So as I need to buy a new monitor for it, what's the smallest size one can realistically get away with?

2
General Mach Discussion / Boxford AUD stepper sizes
« on: November 29, 2012, 04:32:11 AM »
Hi guys,

When I've got the Bridgeport up and running my next project will be the Boxford lathe.  I've had a look in the section about 'your machines', had a look at Hood's ML10 based lathe already.  So far not found the info I'm after.  What would be a recommended size of stepper for the X and Z axis?  I'm guessing that the Nema 34 8.5Nm steppers I'm using on the mill are well overkill...especially for the X axis, not to mention the bulk, Z perhaps it would be ok, afterall thats where the majority of the cutting load would be.

Can anyone suggest suitables?  The current leadscrews are 3/4" for the Z and 7/16" for the X, (doubt they're metric) I was originally intending using them to start with, using the half nuts for the Z movement as there's next to no wear in them.  Ultimatly they would be replaced with ballscrews.

3
Show"N"Tell ( Your Machines) / My Bridgeport clone project
« on: October 24, 2012, 11:53:31 AM »
Hey guys, its about time I started a thread for my project.

Its a 1991 'Lillian', a Taiwanese clone of a Bridgeport.



I bought it from work when we scrapped it.  The motor threw its bearings and chewed up the stator, with repair costs being more than we though worth, and the old 2-axis CNC system was on its last legs.

I've got it a brand new motor and a Variable Speed Drive which I'll control with a 3-step pulley setup I've made, and use Mach 3 to hopefully control the motor.  Servo drivers being expensive, and needing to add the third axis anyway, I've opted for 8.5Nm stepper motors from Zapp Automation, driving through 2:1 belt drives.  So far, I've only got the long axis set up, and I think I've got some backlash somewhere that I'm trying to trace.  I have started work on the short axis, and got a Bridgeport Z axis for it.  It may be the Z which gets done next I'm not sure, a little bit of modification is required to mount the motor as the mount holes are a different pitch to the old ones. 













More to come as work progresses  :)

4
Is there anything special I need from a VSD for Mach3 to control it?  I want to get the VSD so I can start wiring up the mill to do one quick job which only needs manual, but I want to get the right one that can then be re-wired for Mach.

Thanks

5
General Mach Discussion / Encoders - fit or forget?
« on: August 14, 2012, 07:34:58 AM »
Before I get too carried away, I'm considering the fitting of encoders to my Bridgeport clone conversion.  The Steppers I have are dual ended, and the X ballscrew at least has excess length so I have two options for the mounting of encoders.

Coming from an industrial background, it is my intention to fit home switches so I can reference the machine every time I power down, I know steppers can loose count sometimes so the ability to reference is important to me.

Question is though, is it worth me fitting encoders aswell?  and if so, to the back of the stepper or the end of the ballscrew?

Thanks

6
General Mach Discussion / Zapp Automation - anyone used?
« on: July 26, 2012, 05:09:08 AM »
Apologise if this is in the wrong section but I couldn't find anywhere better.

I'm looking to purchase one of the Nema 34 8.5Nm steppers I plan to use on my Bridgeport clone, as I'd like to have one in my hand while building the mounts and everything.  Zapp is currently coming up as the cheapest supplier, has anyone used them before?  Any experinces to share?

7
General Mach Discussion / Spindle speed sensing on a Bridgport
« on: July 25, 2012, 01:48:17 AM »
Hi guys,

I'm finally making progress with my NC conversion of my Bridgeport Series 1 clone - guess I'll be around a lot from now on!  I've got the head all in bits removing the quill self act and stuff, and it's in need of a new drive system anyway, and while I'm in deep I was looking at fitting the spindle speed setup, so I don't have to take it all apart again. 

As I see it, the only sensible place to put it is below the back gear on the splined end of the spindle.  That is always going to be true spindle speed then, instead of having to work it out from the top pulley or some other bit of the drive system.  I reckon a proximity switch would work well, its what we use at working for counting rope lengths, and they are very acurate and trouble free.

I've been doing some research and found that Mach3 looks for one input per rev to work with the C3 card to generate a spindle speed readout.  Can the system cope with more inpulses?  I was oriignally thinking about bolting a block of stainless onto the side of the splines to trigger the proximity switch, then hit on the idea of setting it up to see the high points of the splines, which would mean 6 impulses per rev - is that possible?

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