5C spindle modification for Tormach mill ?

[DLawrence]

I am getting back to my Tormach 1100 and am still interested in the idea of a 5C spindle for the main spindle. I cant seem to find anything on this, wonder if anyone ever went ahead with this type of project ?

Thanks,
Dave Lawrence

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[kstrauss]

The OD of a 5C collet is almost 1.25 but an R8 is only about 0.95 (see R8 and 5C Collet Dimensions | Metal Arts Press). What is the ID of the lower bearing in the spindle?

[GLCarlson]

The OD of a 5C collet is almost 1.25 but an R8 is only about 0.95 (see R8 and 5C Collet Dimensions | Metal Arts Press). What is the ID of the lower bearing in the spindle?

1.565" more or less. So you've got about a 0.15 wall, vs a 0.3 wall. Might get interesting.

[kstrauss]

1.565" more or less. So you've got about a 0.15 wall, vs a 0.3 wall. Might get interesting.

You considerably over-estimate the wall thickness without replacing the bearings since a 5C collet uses a drawtube rather than the drawbar of R8.

I'm curious though. Why would you want 5C?

[RussMachine]

I'm curious though. Why would you want 5C?

My thoughts exactly.
Why would you rather have 5C instead of R8?

[Steve Seebold]

When I got my 1100 in July of 2011, the first thing I did was put a 3/4 inch HARDINGE R8 collet in it. I have never changed that collet and even after thousands of hours, I can put a 3/4 inch dowel pin in the spindle and when I put an indicator on that dowel pin it looks like the indicator is stuck.

The collet that came with the machine was good, but the HARDINGE is better.

AND, a 5C collet has external threads while an R8 has internal threads.

[jttoner]

Steve, I'm convinced and will order a new Hardinge, but doesn't Tormach's have some unique feature that allows it to work with the TTS system?

[jwatte]

The main unique part of TTS is an R8 3/4" collet with a flat (rather than rounded) bottom face.
The flat face means that it fits inside the turned groove on the top shoulder of the TTS holder itself, so the ground reference face of the shoulder clamps straight against the bottom of the spindle.

[DLawrence]

My motive for a 5C spindle is for using the machine as a vertical lathe. I have an ongoing job of creating quantitys of a gearblanks ...its just under .750 diam, I am doing it on a manual turret lathe , using a Warner Swasey M1372 roller box tool I can easily hold close od all day long. Would like to start making these on the tormach , and dont want to give up the roller box...think its a little large to hang up there for going to a rapid turn. So I could plug off 3 blanks per load as is, since this is a yearly run of 3500 , seems like a spindle modification that would allow a longer rawstock slug might be worth building. Not looking at 5c for increased diameter at this point , just increased depth. I think a spring loaded bar puller would work if I had some length up in there to pull.

Thanks Dave

[SCzEngrgGroup]

Buy something like this:

https://www.ebay.com/itm/5C-Collet-C...alq4:rk:7:pf:0

Make an adaptor to attach it to the existing R8 spindle. You'll likely need to make it fully adjustable (both concentricity and co-linearity) to get acceptable runout, given how long it will be.

You can also get small R-8 shank 3-jaw chucks. Use one of those, and use a grinder to true up the contact faces on the jaws.

Regards,
Ray L.

[Steve Seebold]

The main unique part of TTS is an R8 3/4" collet with a flat (rather than rounded) bottom face.
The flat face means that it fits inside the turned groove on the top shoulder of the TTS holder itself, so the ground reference face of the shoulder clamps straight against the bottom of the spindle.

I used mine just the way it came out of the box.

[Steve Seebold]

My motive for a 5C spindle is for using the machine as a vertical lathe. I have an ongoing job of creating quantitys of a gearblanks ...its just under .750 diam, I am doing it on a manual turret lathe , using a Warner Swasey M1372 roller box tool I can easily hold close od all day long. Would like to start making these on the tormach , and dont want to give up the roller box...think its a little large to hang up there for going to a rapid turn. So I could plug off 3 blanks per load as is, since this is a yearly run of 3500 , seems like a spindle modification that would allow a longer rawstock slug might be worth building. Not looking at 5c for increased diameter at this point , just increased depth. I think a spring loaded bar puller would work if I had some length up in there to pull.

Thanks Dave

I use a TTS ER-32 collet holder for turning.

[kstrauss]

Are the blanks just under or just over 3/4-inch (R8 collets are available in diameters of up to 1-inch in increments of 1/32-inch)? How long is each blank?

[tmarks11]

My motive for a 5C spindle is for using the machine as a vertical lathe. I have an ongoing job of creating quantitys of a gearblanks ...its just under .750 diam,

So why don't you just chuck them up in a 3/4" R-8 collet? Assuming your raw stock is 3/4" in diameter? Or a 7/8" R-8 collet with slightly larger stock?

Or if they are undersized enough that the R-8 collet won't grip them, try to see if there is a metric R-8 collet that works better.

Failing that, get an R-8 emergency collet blank and cut it to the exact size you want.

https://www.shars.com/r8-emergency-collet

[jwatte]

why don't you just chuck them up in a 3/4" R-8 collet?

I think he wants to use the spindle as a semi-chucking collet. I e, he wants to hold, say, 12" of stock, turning out a 2" piece, moving it down 2", turning out another piece, ...
The longer you can make the stock when you start, the less you waste in "holding area" for that last stump you can't really machine.

I think an actual lathe is probably a better option ... What with buying new tooling as well as the cost for a spindle change, getting a mini/small/cheap CNC lathe might be doable. (Something like mini-lathe + stepper motor conversion, or Shopmaster lathe.) Of course, those options won't be as rigid as the Tormach, so the details of the work matter.