[handlewanker]

I'm honestly really confused here. What forces do you think the belt will exert on the spindle? Putting my full weight into it, I can't deflect it more than a couple thousandths. the belt has much less tension than that. side load is being supported by AC bearings in the quill portion.

Hi, that was just my personal opinion, take it or leave it........the top bearing is there to ensure concentricity of the spindle under cutter forces that apply a side loading to the bottom of the spindle and a corresponding opposite side deflection to the top of the spindle due to it's leverage over the length.......it can pivot in the bottom angular contact bearings when loaded, etc.

As you were working on fitting a top bearing to the spindle I suggested that you "could" have fitted two SAME SIZE bearings, one on top of the other, in a deeper cup housing and so increase the loading capability of the spindle at that point.

The force of the belt will impinge on the bearing oil/grease film and thin it out thereby making wear in the bearing an increasing factor, precisely where you don't want it.

As you've finished the job it's now merely academic, no more to be said.
Ian.

[mactec54]

BTW........it is not a perfect mod, as the spindle top support bearing is now being forced to resist the side loading from the belt........that is extremely bad design in a milling spindle......more akin to a drilling machine design

And of cause you have Built Spindles to know, that this would be a bad design, if this is a bad design then all Bridgeport machines & clones, have a bad Designed spindle as well, because this is the same as what they have, I Design/build many custom spindles,I also used to build custom prototypes Bearing assemblies for SKF, you should stick to subjects that you do have some experience with instead of pretending, there are a lot of people that pretend, to have knowledge on subjects,but just leads to confusion for the person that is looking for support

[handlewanker]

You mean in this design that it's perfect having 2 angular contact bearings, one at top and one at bottom in the quill???.....you're kidding me.....and the previous bearings were deep groove radials that he replaced with the angular contacts......in a mill spindle????

I'm outta here....this is too much to even think about.
Ian.

[hanermo]

Exactly.
Agree with mactec, and Bp spindles are indeed just as he said.
So are many lathes.

...if this is a bad design then all Bridgeport machines & clones, have a bad Designed spindle as well, because this is the same as what they have, I

[mactec54]

You mean in this design that it's perfect having 2 angular contact bearings, one at top and one at bottom in the quill???.....you're kidding me.....and the previous bearings were deep groove radials that he replaced with the angular contacts......in a mill spindle????

I'm outta here....this is too much to even think about.
Ian.

We were not talking about how this spindle was made or designed, is it ideal the placement of there AC Bearing no, But the support Bearing placement, that has been implemented, is as good as it gets, for a spindle like this, anyone that has a mill like this is working with what they have, & most don't know how to make changes, to the existing spindle to make it better

[bhurts]

I thought it a very elegant solution considering what he had to work around. There is one thing I would have done differently. It has nothing to do with the bearings. It looks and I may be wrong like the center hub that goes around the spline shaft was made from aluminum. I would have made that part from steel out of fear it would deform and allow some play over time. I am just a machinist not a engineer so I may be wrong. I wouldn't change a thing unless it becomes an issue.

Ben

[handlewanker]

OK Mac....I suppose the "working with what you have" is correct for this case.

The jig borer I have also has a quill but it's belt driven from day one.

The quill bearing arrangement for that also had the ang con bearings at top and bottom of the quill.....seems to work but not ideal, but for boring and drilling is all down pressure etc.

In a redesign I shrunk on a larger bearing cap to the bottom end of the quill (losing 25mm of quill travel) and fitted two ang con bearings of significantly larger diam to fit an R8 spindle in place of the original Morse 2 one.......long story.

It's probably too off topic and not the place to suggest a complete quill redesign in this build, although with a redesign I think the poster has the ability and facilities to do it, and someone must have already gone down that path before.
Ian.

[bhurts]

I am no expert on jig borers but I do have a working knowledge and fair amount of experience with jig grinders. I'm interested in the model you have so I can compare it to the only ones I have used. They are all made by Moore and none of the have belt driven spindles that I have used. The are super accurate and can hold true position tolerances close to .0001. They can also grind journals and give finished hole tolerances as close as .0001 tir. Looks similar to a Bridgeport with a giant micrometer built into the top of the head for making
adjustments. They use air spindles and run on the order of 60000 rpm.

To the op sorry about the off topic question just curious. If it is out of bounds you can have this post removed.

Ben

[handlewanker]

Hi, it's a Beradi jig borer, Italian make, bought 2nd hand in the late 70's.

In this build I'd think a spindle could be custom built to replace the quill and be fitted in the head casting along with a proper bearing arrangement........but that's another story.
Ian.

[bhurts]

Thanks I'll check it out.

Ben

[mactec54]

Hi, it's a Beradi jig borer, Italian make, bought 2nd hand in the late 70's..

This thread is not about a Jig Borer or your SVM-0 mill, ( when you get it, ) I hope you are not too surprised when you do get it, as to how small it really is,it will be a good machine if you are into watchmaking or circuit boards Etc

In this build I'd think a spindle could be custom built to replace the quill and be fitted in the head casting along with a proper bearing arrangement........but that's another story.Ian.

Then this is a Great opportunity for you to build a spindle kit, for these machines, we know that talk is what it is, doing & completing ( 1 ) would be something else, but would make a good thread though