Would a Bridgeport J-Type be a good candidate for CNC conversion?

[crazyman]

What should I look for in terms of the J-Type models for later CNC conversion?
What would be needed in parts ito refurbish a used one? Also cost to refurbish?
And what disadvantages to going with this J-Type instead of a a series I Bridgeort?

[mxtras]

If there are reasons why it is not a good candidate, I am not aware of them - but I am all ears - that's what I am getting ready to do.

I JUST completed a complete J-head machine rebuild (about 2 weeks ago). The machine was made in late 1965 and was in original condition. The ways were in very good condition, chromed with only light wear - minor scoring - probably because it had grease fittings on it for the ways. I replaced them with a home grown central lube system.

It cost me about $600 or so to refurbish - I had to replace a bunch of stuff in the feed mechanism. I started with a decent machine, I guess. I have heard of folks spending quite a bit having the column, knee and saddle re-done, so I guess the cost depends on the condition of the machine. The one I did was in reasonable condition.

It took me about two months working in the evenings only.

I used a VFD for the motor for the step pulley head. The Series 1's were variable speed with a bit more HP - other than that, the older machines were equivalent but, in my opinion, had better castings than the machines built in the 70's or early 80's . With the VFD, I prefer the step pulley machine as you don't have to re-build the variator every three or four years.

There is a guy on this forum that worked with Bridgeports extensively - I am sure he will post on this topic. ....he speaks the truth.

Scott

[Karl_T]

I'm sure you can retrofit a 2J to CNC but it will cost you more than starting with a series 1. I see these advantages with a series 1;

1. Cost for a series 1 can be lower especially if the machine has a dead BOSS control. (most do) There's A LOT of these macines around.

2. The Series 1 already has ball screws. You'd have to add these to a 2 J. The Z axis would be a special pain here.

3. The series 1 already has LARGE stepper or servo motors. Again you'd have to add these plus a mounting arrangement on the 2J

4. Limit switches are already in place on the series 1.

Karl

[machintek]

As a clarification, the question was about a J head machine. The odds of finding one in very good condition are slim. As someone already stated, it would be best to find old CNC iron. It already has ball screws, chrome ways, some sort of motors WITH mounts, and an automatic oiler. The J head will not have an automatic oiler, may or may not have chrome ways, very slim if it will have ball screws (even if so, they may be rolled-not ground), will not have motors or mounts, etc. Newer iron would have servo motors with velocity loops and position loops. Older iron would have stepping motors with no position loop nor a velocity loop. A lot of effort and money could be saved by finding CNC iron. Just my 2 cents.

George

[mxtras]

The Series 1 machines I looked late last year were pretty sacked-out. I wanted CNC and accuracy, and I think I made the right choice by buying a one-owner J-head that was cared for like a child - I know I got lucky by being patient. For the money I think it was the right choice for me. I am going to have a near-new accuracy level and closed-loop CNC for under $4400 (+many, many man hours) when I finish mounting the components.

My rational for the direction I chose to take was based on the thought that the cost of the Series 1 machines when they were new likely channeled most, if not all of them into production shops where they were run until they became maintenance pigs, then they get shuffled to "our" side of the fence - sacked out, patched up and tired. I have rarely seen a machine shop sell a machine that is in truley good condition overall - unless they were closing their doors.

If you are able to find a decent J-head to start with, I think it is a worthy candidate for CNC as it is a good quality machine with rigidity, potential accuracy and substatial capability. I guess it depends on your expectations and ambitions - my experience has been good so far.

By nature of this forum (home CNC), some are just looking for a project they can call their own.

Scott

[Bloy2004]

lets see some pictures!

[mxtras]

I know, I know....I was hoping nobody would notice the lack of photographic evidence!

I got my first dig-it-all camera last week...my G/F finally dragged me into the 90's!

I'll post some photos this weekend - just to keep you happy! <-- I think that is hilarious!

Scott

[galleta 118]

Hola a todos:
Estoy interesado en localizar un fabricante de MINI tornos CNC podeis darme alguna dirección, en la actualidad tengo un torno Chester 920 a ser posible no quiero transformarlo, sino comprar uno totalmente equipado.

Galleta 118