Off-sized spindle mount

[Luke Maddux]

I've been rehandling my (joinery) chisels recently. The ideal size for a spindle for these is 35mm squared and ~160mm in length.

I need to mount the end in a scroll chuck with the live center, turn a dovetail, remount, shape the handle, remove the live center from the equation, and then turn the rest of the piece while it's freely spinning so that I can test fit the socket. Similar to how you would have something mounted that you were boring out.

I've been finding that, at 35mm, there is a very small margin for error when turning my dovetail, and it is easy to get it too small. Not a crisis, it just means I have to turn it back around, turn another one, and try again. The woods I'm using are figured and pricey, so I don't want to increase the size unnecessarily. The problem is that my standard sized jaws are minimized at around 31mm. Beyond this, it seems that you get down into the Pin Jaw sizes, which are inadequately small.

So I have two questions...

1. How does everyone feel about having freely-spinning spindles which are mounted on a square end in round jaws. I am of the school of thought that this is unsafe, but I'm open to being told otherwise. Mounting square would solve the problem.

2. Does anyone have a simple jig or otherwise means of decreasing the minimum diameter which a standard sized scroll chuck jaw set can safely clamp? I would need to "chock" the chuck about 3-5mm on each jaw to adequately downsize.

I hope that's not too difficult to understand...

Thanks a lot,
Luke

[dai sensei]

Why aren't you just turning between centres?

[Luke Maddux]

Why aren't you just turning between centres?

The chisels are socket-style chisels and I have to make multiple test fits of the socket taper in order to ensure a proper fit.

[dai sensei]

Still a between centres job, you can remount spindles between centres to enable trial fits.

[pommyphil]

Before scroll chucks they would have used a cup chuck, quick, simple and safe. Phil

[Luke Maddux]

But in order to do that, I would have to make a divot in the end of the socket taper in order to secure the live center end. This seems likely to split the taper and make me lose the (aforementioned expensive) blank. I definitely won't be going this route.

Either way, maybe just forget I described the project.

New description:

I need to bore a spindle that is 35x35x160.

Now see questions 1 and 2 from original post.

[dai sensei]

You could use pin jaws in your chuck but I would still be using tailstock support, so you would still have a divot as such, the trick is not doing up the tailstock to tight.

[oreos40]

do you use a steady rest? you could chuck the square in the chuck no trouble then shape the handle and remove the tailstock center and use a steady rest to finish the socket end. Then take your time with the final shaping of the butt end and part off. sand the nubbin to finish the way you like.

[Luke Maddux]

do you use a steady rest? you could chuck the square in the chuck no trouble then shape the handle and remove the tailstock center and use a steady rest to finish the socket end. Then take your time with the final shaping of the butt end and part off. sand the nubbin to finish the way you like.

That's similar to what I've been doing, only in lieu of the steady I just make sure I've got a super solid dovetail mount and I just turn it freely spinning.

[brendan stemp]

In answer to your first question; is it unsafe? Well, whats the worst that can happen? The wood can come out of the chuck and hit you in the face. Not too much of a problem if you are wearing a facesheild. So, if you are doing it this way already why not keep going.

However, I agree with Dai Sensei. I would turn most of the shape with chuck and live centre in tail stock and take the tail centre away for the final shaping of the end. The live centre wont split your wood unless you over tighten it into the end. And to do this you would have to be applying a bit of pressure. I would confidently do this no matter how special the timber, especially 35 sq.

To your second question; sorry I don't quite follow what you are asking.

[Luke Maddux]

In answer to your first question; is it unsafe? Well, whats the worst that can happen? The wood can come out of the chuck and hit you in the face. Not too much of a problem if you are wearing a facesheild. So, if you are doing it this way already why not keep going.

However, I agree with Dai Sensei. I would turn most of the shape with chuck and live centre in tail stock and take the tail centre away for the final shaping of the end. The live centre wont split your wood unless you over tighten it into the end. And to do this you would have to be applying a bit of pressure. I would confidently do this no matter how special the timber, especially 35 sq.

To your second question; sorry I don't quite follow what you are asking.

I think we interpreted Dai differently. When he said "between centers" I was thinking both a drive and a live center. I wasn't thinking about the chuck being on the drive end. I guess this makes sense though. The live center adds some stability to the potentially unstable "square in a round chuck" mount. If that's what he meant then I now understand and think that's a very good idea.

As far as question two, the problem I'm facing is that my standard jaws are JUST too big and the next size down is too small, so is there some way to "step down" the minimum diameter which can be clamped by standard jaws. Like a jig or a trick of some sort.

Cheers,
Luke

[Gabriel]

I may not be following the questions correctly, but if you wish to hold a square spindle in your jaws to work on an open end, what about pen jaws for your chuck?
they are designed to hold a square timber (and 35mm would fit fine) for drilling one end. I know the forces exerted would be different but they're pretty bloody sturdy. Maybe start by turning your tenon with the 'to fit' size, then make a jamb chuck of similar size to the socket in the chisel to attach to a live centre, then finish the handle between centre's?

If the size of your chuck is an issue, they have a pen jaw set from psi (I got mine from pops shed) that is a just for this purpose and only about 60mm diameter.

http://www.pennstateind.com/mm5/merchant.mvc?Screen=PROD&Store_Code=PS&Product_Code=CSCPENCHK&Category_Code=pen-blank-drilling-chucks


Just a thought, if I understood the question properly.

Good luck with it. ....

Cheers
Gabriel

[joe greiner]

I think we interpreted Dai differently. When he said "between centers" I was thinking both a drive and a live center. I wasn't thinking about the chuck being on the drive end. I guess this makes sense though. The live center adds some stability to the potentially unstable "square in a round chuck" mount. If that's what he meant then I now understand and think that's a very good idea.

As far as question two, the problem I'm facing is that my standard jaws are JUST too big and the next size down is too small, so is there some way to "step down" the minimum diameter which can be clamped by standard jaws. Like a jig or a trick of some sort.

Cheers,
Luke

You don't need to step down the jaws; just step up the workpiece - by many wraps with masking (or other) tape. Make the final size large enough to engage the corners of the jaws. In effect, you have very stable square mounting in "square" jaws.

And plus one for the steady rest.

Cheers,
Joe

[Scott]

In situations like this I've used hot melt glue to mount the timber to a piece of pine mounted in a chuck with a live centre at the other end. That's if you're concerned about your fingers. You could also use a collet chuck once you've rounded up your work and have enough to hold onto. There are an infinite amounts of ways to mount your work but at the end of the day the best way is what you feel comfortable with (as long it's 'safe').

[Mobyturns]

Q1. - many turners do this regularly. I agree not the best or safest method however it can be done at a pinch if you are aware of the hazards.

Q2. - depending upon the final tool handle diameter there are a few options.

One of the safest chucks for small dia spindle work is a collet chuck similar to the Vermec ER25 or ER32 http://vermec.tripod.com/PDFs/ER32_Page.pdf.

The ER32 is more flexible as it covers 2 mm to 20 mm collets. To make a chisel handle it is a simple process of first mounting the blank between centers and then turning a temporary tenon to suit the 19-20 mm collet. Mount the blank tenon in the ER collet chuck. Turn to suit the ferrule using the tail stock for support between chuck & live center. The tail stock can be withdrawn to test fit then put back in place. This method will require sacrificing some 20 or 25 mm of blank length.

Another option if you do not wish to purchase a collet chuck is to use a sleeve of PVC - a 12 - 15 mm high ring from 35 mm PVC pipe with a small section of the circumference removed. Place the sleeve between the round work piece & chuck jaws & bring up the tail stock and turn using the tail stock. You cannot use a tenon dovetail with this method.

Make a temporary dovetail disk from a waste wood blank to fit the chuck jaws, as you would for a glue on tenon for a bowl blank. Make it so that it sits proud approx 10 mm or so from the face of the jaws. Use a suitable size forstner bit to drill a socket into the disk to make it into a donut ring. Then make a radial cut with a bandsaw so that the ring can clamp down (close up) on a turned tenon on your chisel handle blank when the chuck jaws are tightened.

I'm not a fan of using pin jaws in compression mode especially any pin jaw set with only one cap screw on the outer rim. The two cap screw pin jaws are a little safer.

[Luke Maddux]

Another option if you do not wish to purchase a collet chuck is to use a sleeve of PVC - a 12 - 15 mm high ring from 35 mm PVC pipe with a small section of the circumference removed. Place the sleeve between the round work piece & chuck jaws & bring up the tail stock and turn using the tail stock. You cannot use a tenon dovetail with this method.



I like this...

[powderpost]

Still a between centres job, you can remount spindles between centres to enable trial fits.

I agree with Neil. Mount between centres and turn round. Fit a ferrule if needed to the top at the headstock end. Turn to shape with the taper on the tailstock end using a revolving centre. Remove the tailstock from the job, mark a chalk line on the taper and check the fit by rotating the chisel. The cone centre should accurately fit back into the hole on the end of the cone. Polish if necessary. When the fit is satisfactory, part the surplus timber off from the headstock end with the long point of a skew. No real need for a chuck.

Jim