I am looking to buy a Bridgeport CNC milling machine.
This is for home / hobby use. I have been looking at Interact machines.
My question is what is the oldest machine / controller that would have the capability to add a 4th / 5th axis at a later date if I wanted to?
I am looking at older machines due to price. However I have noticed there doesn't seem to be much difference price wise between a series 1 interact and some of the later models.
Whether I would ever get round to adding another axis is questionable but I though as I haven't got the machine yet then the capability would be a good thing.
Thanks for your help Dave
The older you go on the machine the more likely the controllers will be dated. The machines are very sturdy and capable which really makes them prime material for retrofit to newer controls. There must be dozens of conversion stories on cnczone.
I have not worked on the electronics of the interact so cannot say which way to go with the conversion in terms of motion control. They probably have analogue intputs to the servo drives, maybe Jazz can chime in, but once you have installed the motion control, you can then add up to 6 axes in total with Mach3/4.
You are going to need to make changes to the motor spindle electrics anyway do work off single phase.www.emvioeng.com
Stocking more goodies than just Smoothsteppers
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There are also couple of types of heidenhien controls used on old interacts with either sinusoidal or square wave encoder outputs which makes a difference if you decide to retrofit the controller. In general Sinusoidal type is start again with new every thing.
Square wave then you can just replace the control with Analog Controller like the Cslabs IP-A or Kflop etc and re-use the Amp's and motors. Easy enough really but does require some knowledge regards wiring and setup etc.
One other thing thou often the Encoders on older motors, Often SEM motors on Bridgeports are Single ended not differential so will need either replacing or special circuit to make into differential that modern controllers require.
Often you'll see many retro-fitted with Modern controllers and Large Stepper motors to avoid all this and just use normal Step-Direction controller and cheap-ish drives/motors. This will how ever often come at the cost of performance.
Now personaly I wouldn't go with either route but would instead gut the lot and replace with AC servos from China and use Modern Step-Dir controller like the CSlabs IP-S. The controller you use for retro fit is important because of the I/O it offers and MHz rating.
Better still if the AC servo drives have Encoder outputs and can accept Analog signals I'd go with IP-A controller for the advantages that it feeds back position to Mach3 at all times. (Or Kflop and Linux or Mach3) This gives the advantage of always knowing the axis position even if axis moved by hand when turned off. Think of it like a manual DRO.
Often the I/O used on rest of the machine is 24V so the controller needs to be able to accept 24V signals otherwise your into converting 24V down to 5V which the Controller or BOB can accept. This quickly becomes a pain also 5v is much more open to noise issues and best avoided for this and reliabilty reasons.. . Not to mention sanity.!!
Spindle Motor and the variable speed pulleys are often a problem. Often these are dealt with by removing the variable pulley for speed control and replacing with Fixed pulley and VFD sized to match the motor. The motors are often Dual voltage so with a quick wire change can be used with 1ph 240V VFD.
This IMO is the best most pain free way to deal with a OLD machines using aged technology. Also won't cost anymore in the long run because you'll probably end up doing it anyway sooner or later.!! . . . Or spend more time chasing problems than cutting.!
Your also very much more flexible regards upgrade options like 4th 5th or 6 axis and ATC etc.
Last edited by JAZZCNC; 04-11-2015 at 07:19 PM.
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Thanks for the informative replies.
You both made a very good point about the ageing hardware.
Look like I will concentrate on finding a machine in decent mechanical condition for the right price and budget in enough for a hardware upgrade.
Had a look at the CSlabs web site I see you can get a 6 axis controller for around £500.
What size AC servo would you recommend looking for?
I guess if I wait long enough a good machine will come up with a hardware fault.
Wouldn't get anything before having the machine. was just browsing the web looking at AC servos out of curiosity to try and ascertain a rough price.
Yes the Chinese drives won't match in quality and probably accuracy compared to the big boys but they will more than match anythign I'm going to challenge them to do.
They have all the same Spec regards Encoder counts and I/O etc the better brand offers and so far they look like they are goung to be perfect for my needs.
Time is a good tester but I'm very experienced at testing things and you get a feel for when some things right and when they are just a little too cheaply made.!! . . . These feel dead right and I'm getting very good vibes from them ( Well actually I'm getting No vibes because they are super smooth. . Lol)
Watch this space because I will shout up if the vibes turn into Shakes.!!
Last edited by JAZZCNC; 07-11-2015 at 01:05 AM.
Sinusoidal Signals can be easily converted into TTL RS-422. There are some Chips from IC-haus that make this without big effort. And the price is ridiculously low compared with a HH Exe.
Jazz, is it possible to add linear scales to a IP/M or S control. I have now the "little" Boxford machine and want to convert it later to a servo control, I already have the Motors from Yaskawa and 2 drives for it but they want analog +/-10V. Now I need 3 additional drives for X,Y,Z and another one for B. If I see it right, I have 2 additional analog outputs which can have +/- 10V.
One for an additional 5th axis and one for the spindlemotor which I will change for a much stronger one.
But it were better, if I can add a linear or rotational scale to any axe.
I know the IP/A can make this, but this part is too expensive for me. With all features I want have, it costs more than 1000€.
The IP-S and IP-A are almost the same price so if you can use Analog -/+10v then I'd go that route.
Or look at the Klop and Kanalog route which seem a nice enough setup, thou again not cheap by the time you have expanded it. Will probably be about same money.
Pokeys 57cnc is worth a look and will support high speed encoders. It also has one of the best Mach4 plug-ins out there.!
I have downloaded the additional manual for the Enc Box. There are 3 Encoder inputs and this part should run with the IP/M Box as well. What can I do with the third Encoder? Or better, is it possible, to connect 2 enc boxes to a IP/M? Than I had 6 encoder inputs 1 for the spindle and 5 for all the axes.
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