Is it feasible to make a new spindle?

[David Kirtley]

It is going to be concentric as you are turning it in place on the spindle. If you are cutting in the bore, same thing. Just like turning a part deep in the chuck. I can't say though that I would risk turning an already thinned spindle bore in place on the lathe. How much has it been thinned? How much more can you take off before you have to worry about it deflecting under a heavy cutting load?

It doesn't have to go down in the bore of the spindle. It would be a pain to put in and take out anyway. Just make a collet holder that fits on the end of the spindle like a chuck. You get the advantage of the larger bore and don't lose that much room on the bed. A 5C collet holder is about the same thickness as a chuck. An ER holder is much thinner. Personally, I prefer the ER collets for their wider gripping range and easy accessibility. I have an ER32 on my lathe and mill, and a spindle collet chuck for my wood lathe and only have one set of collets.

 

[ycroosh]

It is going to be concentric as you are turning it in place on the spindle. If you are cutting in the bore, same thing. Just like turning a part deep in the chuck. I can't say though that I would risk turning an already thinned spindle bore in place on the lathe. How much has it been thinned? How much more can you take off before you have to worry about it deflecting under a heavy cutting load?

It doesn't have to go down in the bore of the spindle. It would be a pain to put in and take out anyway. Just make a collet holder that fits on the end of the spindle like a chuck. You get the advantage of the larger bore and don't lose that much room on the bed. A 5C collet holder is about the same thickness as a chuck. An ER holder is much thinner. Personally, I prefer the ER collets for their wider gripping range and easy accessibility. I have an ER32 on my lathe and mill, and a spindle collet chuck for my wood lathe and only have one set of collets.

David,
I looked around for collet chuck plans and ER-32 or ER-40 looks like a much less painful compromise. I was stuck on C5 chuck, and that appears to be a bit more involved project...
What are the advantages of C5 collets, by the way? It appears that the commercial chucks are mostly C5...

Thank you
Yuriy

 

[David Kirtley]

No expert but for what I know from reading, the C5 (and others in the series) used to be the go-to collet. They have the advantage that they have a draw bar to tighten, commonly available, pretty cheap, lots of different shapes available such as square and hex.

Since the advent of the ER collets, I don't think there is any advantage to them other than they are still around and you can pick up some nice fixtures for them like spin indexers and such. The ER series collets are better in that they clamp parallel over the entire collet length rather than at one end of the collet like the C collets and R8 and the like. Because they are slitted from both ends with lots of slits, they also have a much greater clamping range. Many times I use them in my mill rather than the drill chuck because they take up much less space than the drill chuck. I have only had one drill bit size (I don't remember which size it was) that I couldn't clamp because it was too big for one size and too small for the next size. You can also pick up metric ones that would fill in those missing sizes. I have not had any problem clamping square or hex stock in the ER collets. I don't even bother putting anything on the threads if I put something threaded in them. They just hold well and they are also self ejecting when you back the nut off.

The only real problem with making an ER collet holder is the closing nut which most people just buy. It is just an 8 degree taper with a metric thread for the nut and whatever you need to hook it on the spindle. Mine uses the same flange that the chuck bolts to. My holder for my wood lathe just screws onto the threaded spindle. There are some less expensive places like CTC tools in HK that have great prices for collets and such. The ER32 maxes out at 3/4in which is fine for me as that is the largest size I can get through my spindle anyway. I believe the ER40 goes up to 1". I would say to go with whatever you might be able to use on multiple machines. You can get R8 holders, MT holders, straight shanks, and others.

I use this style holder on mine (image from Little Machine Shop)

 

[Ray C]

I'm not familiar with ER collets other than what I've read; however, I've been using 5C's for a good while. I do fine by them but wish to state my personal view that they should not be used for holding endmills. They're fine for holding stock and drill bits but I suspect the sideways pressure associated with milling would deform and blow the accuracy of a good C5 collet. I have no evidence to support this and it's based on my personal observations and general "feel" for what 5C's are good for and what I suspect should be avoided...

I'm tempted sometimes to invest in an ER setup but, I have a system that works (for me) and just don't feel like rocking the boat with new fixtures to learn and (attempt to) master.

Guess what I mean is that once you pick a system, get good at it, use it -and only change if there's a compelling reason.

Ray

 

[David Kirtley]

Also as you build up a larger selection of collets and tooling of any kind, the incentive to change reduces dramatically. I already had pretty much a full range of ER32 collets for my mill before I bought the holder for the lathe. It was a no brainer to stick with what I had.

 

[Tom Griffin]

First of all, that you everyone for jumping in.
From the looks of it, getting a new spindle from Grizzly is not that much more than making one, by the time I get the steel stock, reamer etc.
It hasn't occurred to me to make a sleeve adapter, though.
One question, though: how would I make the insert perfectly concentric with the spindle? It looks like there is enough meet to cut a small taper, so would I use that to hold the sleeve true?

Thank you
Yuriy

I would bore the damaged section of the spindle out and make a bushing for it with an interference fit, referring to the Machinery's Handbook for the proper amount of interference. Then take the spindle out, heat it up and shrink fit the new bushing in place. At that point the spindle can be reassembled and bored out to the original taper.

Tom

 

[itsme_Bernie]

Tom has a great idea to actually repair the spindle.

Or you can create an insert (or use some existing one) that has 5C (or whatever you want) inside. Then cut your spindle to take the outside taper of that insert.
That's what SB did with it's 2 1/4-8 spindles on it's heavy 10 through 16 inch models. A proprietary SB taper inside the spindle, and 5C inside.

So if you can pick one that already exists, you can just cut the outside taper and pop it in!


Bernie

 

[hanermo2]

You are overcomplicating it.
Just use a cheap collet chuck and grip in in your 4-jaw (or3-jaw for less accuracy).

No need to dismount anything, if you indicate the collet chuck in the 4-jaw, and better than 0.0005 concentricity to boot.

Making a spindle is quite doable, btw.
Making good bearing mounts, conceentric, is either easy or hard depending on how well you cant to do it, can afford to do it, and how good your bearings and setups are.

There is huge variance.
Some people mount bearings with 50 degree C heat difference, and they just "drop in", and some round/smooth the surface with wet/dry and bang them on with a mallet.
Some people use 30$ generic bearings, and some "spindle bearings" from name brand houses at 300-500$/set, even NOS/ebay.
Neither is right or wrong, it depends.
Many, many people use little 7x hobbylathes with generic bearings with excellent results.
Many people have made grinding and milling spindles with basic bearings, and get excellent results, when the final cuts/tapers/grinds are done running on the mounted bearings.

I am engaged in making a CNC T&C/surface grinder, industrial production quality.
I am using a granite 80kg surface plate as the basis 600x440x100 mm.
About 300 kg, 35 MM linear bearings, 32 mm ballscrws, ac brushless servos.
I expect to be able to make shiny, smooth surfaces to "good" quality.

For some that is overkill, for some its a "crap shopbuilt toy". Depends on what you compare it to.
I dont expect to be able to "guarantee" under 1 micron flatness, but I certainly expect to be able to make spindle surfaces, spindles, bearing surfaces and lathe inserts.
Time will tell, its progressing quite well.