View Full Version : Bridgeport Help

07-17-2009, 11:30 AM
I have purchased 2 machines, a step pulley drive & a variable speed drive(parts). I would like to put the variable drive on the good machine. Can someone tell me if I can unbolt the drive assy w/motor and put it on the good head. I have looked at the parts lists and they do not indicate that there is any difference in the quill housing assy.

07-17-2009, 01:57 PM
Why put a mechanical ancient drive on, when you can go with a VFD???
Variable Frequency Drives and a step pully head are the way to go...

The mechanical Reeves drives system is noisy, wears out often, and costs up to 400.00 to fix each time....

A ~ 200.00 or so VFD will give you variable speed, ramp up and down start stop cycles, and even electric braking all with the standard 3 Phase motor. They also can convert single phase 110 v to 3 phase if needed, with none of the power loss of a Static phase converter, or expense of a rotary phase converter.

07-17-2009, 04:01 PM
The parts that go on the "Reeves" drive most typically are the plastic bushings which cost about $20.....and a new set is not that likely to be worn out in a home shop. The issue is the work that it takes to pull the VS head apart and remove and glue in new bushings.

It's also worth noting that some will propose the use of a VFD as a solution to all speeds. You had better still figure on doing some belt changing because while you may be able to vary the speed of the motor with the VFD, doing so exclusively will put a lot of load on other parts. Think of trying to ride a bicycle in tenth gear all the time and just varying the speed at which you pedal :D Wear and tear on the cranks, sprokets, chain....and especially the rider....would be substantially greater.

Why not swap the entire head? That's done all the time and is the easiest operation by far.


07-17-2009, 08:59 PM
Why not swap the entire head? That's done all the time and is the easiest operation by far.


Thanks Paul for the reply.
The quill assy is not usable as it is rusted up and worn out. Whereas the step pulley drive and quill assy is all good.


07-17-2009, 09:31 PM
I'll second the VFD. I have a round ram Bridgeport with a step pulley J head. The pancake motor runs fine off the VFD. It's the best of both worlds -- the simplicity and ruggedness of the step pulley drive and the programmable features of the VDF. In it's simplest form, a VFD has three wires in (each leg of input and ground) and four out (three phase and ground) and can be controlled from the front panel. Never put a switch between the VFD and motor, either use the front panel or wire in a remote switch to the appropriate terminals on the VFD.


07-18-2009, 08:04 AM
Third on the VFD. You might have to change belts to go from very low RPM to very high RPM, but most of the time, it will probably remain in one of the mid-range grooves.

As far as extended wear, that won't happen any more with a VFD than a Vari-Drive or a step pulley. The drive is essentially a separate unit that supplies the input RPM to the rest of the head.

07-18-2009, 09:11 PM
Third on the VFD.
What is a source for a reasonably priced VFD?

07-19-2009, 09:39 AM
I have 3 Teco-Westhinghouse VFD's purchased from Factorymation http://www.factorymation.com

Their prices are competitive and delivery very good. So far, no problems.


07-19-2009, 10:11 AM
A place called Automation Direct may have VFD's I cannot speak for the quality but they do have a reputation for being very competitive.

07-19-2009, 10:32 AM
Be careful what you choose though - IMO.. you need a unit capable of braking with an external brake resistor. Most cheaper untis are not upgradable later.

I use the Hitachi SJ200 2hp unit on my BP, Hitachi L200 on my lathe and the Teco 1hp units (no external brake) on my surface grinder.

Roy Andrews
07-19-2009, 03:04 PM
i have both rotary converters and a VFD they each have their place. as far as being cheaper than a rotary that is bull. i have built several rotarys and have a 10 hp that i have less than $40 in. some machines cant be run on a VFD. i run my lathe and m head b-port on a VFD and love it. but the KT and the band saw require a rotary so that it can be switched. so look at what your going to do in the future.

07-20-2009, 07:21 PM
I have a GS2 2HP VFD from AutomationDirect for my step-pulley BP. It's very easy to program and set up. I don't have braking resistors and need to set the ramp down time to 5 seconds to avoid faults. This isn't a problem unless you are power tapping on the mill.

07-20-2009, 10:27 PM
I love a VFDs... . but I just ran into into an unexpected issue with my "new" lathe... the oil pump is driven from the motor, and it pumps little oil at low speeds... there is no splash oil bath on this lathe, and I'm not sure low speed means I can use less oil to the spindle.

Many ways around this, but....