JDs BP J-Head CNC Conversion Blog

[mxtras]

Keep up the posts!

Scott

[jdelaney44]

Started a couple of weeks ago. There's this grindy / squeaky noise up in the vari drive that could be the belt but there is a clear metal on metal sound.

Then today when I was cutting with a 2 inch four flute fly cutter I get this rattly sound like a bearing that's run out of grease and is what I call "spinning out"

So into the vari speed I go. If anyone has tips I'd sure appreciate it. I saw the posts on belts and wear in the head. I'll take some pics and post later.

So the quill drive project is going to have to wait a bit.

Nuts!

Update:

I think it was just a loose motor bolt. I tightenned that up and it sounds OK. The belt is squeaky. It is really noticeable at low rpms. I have a VFD so I can slow the motor down. So maybe I'll order a new belt.

-jd

[jdelaney44]

The Bridgeport 2J head is still making the rattling noises. Replies I have received here and a couple other places indicate that the plastic sleeves and keys in the varispeed are probably the culprit. I think I'm going to work it through next weekend and then open it up. Sounds like I'll get a new belt too. Thanks to all who have relpied for all the help.

Today I got the thrust bearing retainer done. Along with that I made a spacer for between the bearings anb another to make up the extra space between the last bearing and the retainer.

I super glued my material to the face plate of my 7x12 lathe to turn it down to size. For the retainer I super glued it to a chunk of aluminum and put that in the vice. Machined it from there. I heard about the super glue trick a couple of years ago on the 7x10 mini lathe group on Yahoo. First time I tried it was this weekend. Worked great. Just take it easy though. Too much force and heat will pop it off. Once your done just get a putty knife under the edge and tap it with a hammer a few times. Should come right loose.

There's a picture of my centering indicator. If you've not used one of these, they are great. there's a probe that rides on the edge of the hole. There's a small bar that lets you keep the body facing one direction as the core turns with the spindle running at a very low speed. The core has the probe on this little two way fulcrum arrangement. As it goes 'round the body moves up and down and the guage moves. The closer you get to center, the less it moves. Minimize the wiggle and you are at center. I use it almost every day I work. Realy helpful when you skip a step by accident. I got that one at Little Machine Shop.

I also took a picture of the quill drive with the parts loosely assembled. Might help see how it's constructed better.

[jdelaney44]

Quick update. Last night I got the end of the ball screw bored and tapped. Used .25 in end mill. Stood the screw up in two V-Blocks. Bolted the whole rig to the table. Centered it with the centering indicator. Still a little wobbly but OK. The .25 would have been too small for the 5/16 tap really. The typical three lobed hole from the wobble made it reasonable to tap.

Once that was done I bored out some washers to go over the .625 screw end and make contact with the thrust bearings. Put the pulley on, added a couple more washers for the 5/16 allen cap screw, cranked it all down and I have a complete thrust bearing assembly! A little loc tite on final assembly and it's good to go.

Now for the link from the nut ro the stock Bridgeport quill and it's done! Yay! Getting close.................

Pics later.

[jdelaney44]

I know this is getting old, but, here's another progress note.

Today we have the link almost done between the ball nut and the quill. I think I can safely say that paper weight #4 has been avoided.

My best efforts to measure everything with no reference points came out pretty good. But I need to elongate a couple of bolt holes to allow for some slop that has built up through all the parts and at least one suspect measurement. (Quill to ball screw) I can't actually get that measurement so I'm having to build it up from several others. Something is off by about .050.

The link is actually a block of steel that is 4.00 long and 3.40 wide. There is a notch that is about 1 x 1 to accomodate the existing scale and the lugs behind it. The nose of the piece is 0.745 dia. and about .40 deep. This let's it clear the face of the casting housing the quill. The 0.745 just fits in the round recess in the quill. It has flats on either side. So the height is 0.745 and the width is 0.62. So its a round nose with the side trimmed flat.

This is just like the depth stop that was removed. Then on the outboard side there is a "U" " cut out to accomodate the screw. Then there are two 5/16 holes to bolt it to the nut.

So next weekend will be spent doing that and assembling and testing the drive with simple fwd and rvrs on the motor.

As soon as my daughter lets me use the camera again I'll post some pics! Argh! Teenagers.........

Thanks for listening.

[Cold Fusion]

It looks great so far. I've got the same kind of project coming up soon, so any threads on the subject of BP retrofit are of much help. All of the pictures have been wonderful! Don't underestimate how helpful they are to all of us.

*All posted by a teenager eager for more pictures *

[Hood]

Been following this post with interest. I am also retro fitting a bridgeport and have the X and Y completed and am using the 2 Axis to machine my Z brackets. I am just behind you in progress, presently I am machining the quill/ballscrew coupling out of an 8.5 inch Dia lump of steel (was only piece handy ) Hope to have it completed this weekend.
Hood

[jdelaney44]

Hood, you are faster than me! Yeah that was the right process. I wish I would have done the x / y first so I had the CNC to work with on the Quill. So you're hogin' out of a chunk of round stock? Cool. Should be interesting.

OK kids, here are pics of my Bridgeport Quill Drive Link. Last part for the Quill drive! Almost done with this and ready to do the X / Y.

You can see the big notch on the side to clear the stock scale on the Bridgeport. The hole is 3/8" to accomodate a 5/16 allen bolt. That ove bore is just shy of .75. .625 would do it, but I did not have a .625 end mill handy. Gotta order a couple tonight.

The big "U" wraps around the screw and the two holes in line with that are for the bolts to connect the link to the ball screw nut flange. Again 5/16. So those are the holes I need to elongate and I need to countersink for the allen bolts.

I left all the material there 'cause I figure it'll help make it stiff. There's a limit to how much is really helping I know. But mass is not an issue for this part so why bother removing material that might help?

Have fun!

-jd

[Hood]

Yep its a big chunk of steel I am hogging it from, stupid really but its all experience LOL. Heres a pic of what I have done so far, going to make a bracket going to the downfeed selector lever to help support the top. Just hope my motor is going to be big enough, was assured by the guy I bought the drives off it would be, but he also said his drives were the best suffice to say I now have Geckos on their way and have already replaced his breakout with a PMDX122
Hood

[jdelaney44]

That looks really good. The screw is real close to the quill. Key point from what everyone says. Did you have to tap the lugs for those smaller bolts holding the back plate on there or were there holes there already on that mill?

-jd

[Hood]

Actually the ball screw is quite a distance from the quill, see new pic. I would have liked it closer. With me mounting the motor at the top I had to leave enough room for a pulley, also the nut on the ballscrew is 50mm Dia so that ddidnt help either. Yes, had to drill and tap the casting, decided it wouldnt do much harm and seemed the easiest route.
Hood

[jdelaney44]

Well, it looks like you'll have plenty of travel. I'm losing .75. Not a big deal but some.

-jd