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TR
09-20-2010, 08:33 AM
I want to fit a d1-4 backing plate to a six jaw chuck. What is the general approach to ensure I drill the 6 holes in exactly the correct spot ?



http://i663.photobucket.com/albums/uu354/topari/DSCN3691Medium.jpg

http://i663.photobucket.com/albums/uu354/topari/DSCN3692Medium.jpg

Davo J
09-20-2010, 08:45 AM
Since the bolts come from the front, after you machine the register use a transfer punch. If you don't have one they are easy to make.

Dave

Edit
Just noticed your from Aus, did you buy that here or over seas? Also what brand is it?

danlb
09-20-2010, 08:45 AM
When I did it, I carefully marked the spots using a compass and divider. When I blew that I rotated it a bit and trasfered the spots using setscrews ground to a point.

In your case, machine the boss first, then use transfer punches while it's mounted to the plate. Your mounting holes go all the way through.

That plate looks a little thin for the set-true chuck. Don't you need about a boss about a half inch high for those adjustment screws?

Dan

TR
09-20-2010, 08:53 AM
@Davo , the chuck was bought in the USA from Shars. Shipping to AUS was under $100. Still cheaper then it would have cost here.
@Danlb, I have several other spare d1-4 backing plates. Interesting you think the plate is too thin.

Davo J
09-20-2010, 08:58 AM
I never realized it was a set true chuck. If you can't get hold of a proper back plate for it, you could machine a small recess in back plate for another piece of round cast to be bolted on for the set true.

Dave

TR
09-20-2010, 08:58 AM
That plate looks a little thin for the set-true chuck. Don't you need about a boss about a half inch high for those adjustment screws?

Dan

Looking at my own pictures, now I know what you mean :)

Davo J
09-20-2010, 09:07 AM
I see Shars has the back plates for $58 and probably another $50 for postage.
If you don't want to buy one my idea above would work if you have a piece of cast, steel could be used if you haven't got cast.

Dave

8ntsane
09-20-2010, 09:40 AM
Looking at your pics, that chuck has through bolts, so Id would use a tranfer punch to do the bolt pattern. On that note, usually transfer punch sets are pretty cheap, and available. There is a few thing to check before using them.
The first thing is make sure the point is on centre. chuck it up in your lathe, and run it slow, if the point wobbles, dont use it! The next thing, make sure the punch fits snug in the holes of the chuck. If it has a loose fit, it will induce error. If you can,t find a good fitting punch, then fire up your lathe and make one.
I would turn it down so it was a nice slip fit, with no side to side movement.
Then you can machine the point, and harden if desired. I asume your going to
machine up a center hub, for the set true function, and and bolt it in. In that case, the step that normally centres your chuck is a bit under size, to make shifting your chuck to centre possible. I would machine this to a snug fit first, then use your transfer punch, to mark your bolt circle, then take off a few thou to allow the set true function to work. As another poster had mentioned, you can machine a step in the plate to hold the hub the 4 set true bolts bear against, and bolt that peice on.

One last thing worth mentioning. If your using the transfer punch method, use a big C-clamp to hold the plate to the chuck, esspecially if its not a tight fit when your ready to punch the bolt circle. Not that the plate can move off centre, but if not tight enough fit, the plate can rotate a bit, and mess up the bolt circle just the same.

I just did 4-backing plates last week for my machine, and if you are carefull you should do fine.

Toolguy
09-20-2010, 09:52 AM
I would get or make the right backplate. Mount the backplate on the lathe with the chuck on the back plate. DO NOT turn on the lathe. Put a dowel pin in the jaws and indicate it in using the set tru screws. They needn't be real tight for this. Turn the chuck by hand while indicating. Then use a transfer punch through the bolt holes to mark the center of each bolt. Remove the chuck and drill on the punch marks. You have a really good chuck there. If you don't use the set tru feature, you will be missing out on how good it is to have a scroll chuck that really runs true. It makes a big difference in the ease and quality of your turned parts.

oldtiffie
09-20-2010, 05:10 PM
@Davo , the chuck was bought in the USA from Shars. Shipping to AUS was under $100. Still cheaper then it would have cost here.
@Danlb, I have several other spare d1-4 backing plates. Interesting you think the plate is too thin.

http://i663.photobucket.com/albums/uu354/topari/DSCN3691Medium.jpg

http://i663.photobucket.com/albums/uu354/topari/DSCN3692Medium.jpg

TR.

That job is best done on a rotary table.

I am in the middle of making adaptor plates for 80mm chucks and face-plates for my universal grinder.

The process is very simple and very accurate on a rotary table.

From the specification sheet for your 6-jaw chuck: what is the Pitch Circle Diameter?

From the specification sheet for your rotary table (if you have one) what is the ratio turns of the worm to the turns of the worm-wheel? In other words, is the rotary table ratio 40:1 (usual) or 90:1 ("Vertex" and similar rotary tables)? If your rotary table has 3 slots the chuck can be fastened to the rotary table and the job held in the chuck.

That chuck is indeed a "Set-True" type as the 6 radial screws locate on and adjust against a spigot on the back-plate.

So that backing plate not only needs six holes drilled in the face of it for the six hexagon-headed socket screws (HHSS) but also needs a spigot turned on it (for the radial "set-true" screws to adjust the chuck). Those details will be on the specification sheet for the chuck as well.

Please either scan and post the pic of the specification sheet for the chuck or provide the link at Shars for it - or better still - provide both.

[Edit]

OK - I have the detail from Shars - is this it?

http://www.shars.com/products/view/994/Adjustable_Universal_Chuck_6quot

[End edit]

The Fixer
09-20-2010, 05:25 PM
In a pinch when I didn't have transfer punch set I'd select a drill bit of the proper fit and freehand a shallow point on the shank end on the bench grinder. drop it in the hole and hit with a deadblow hammer, works like a hot damn.
al
P.S of course I could have got a piece 4140, drill rod, or some such and turned it on the lathe, heat treated it and ground it in the centerless..... but the drill bit just seemed easier!

oldtiffie
09-20-2010, 08:49 PM
I want to fit a d1-4 backing plate to a six jaw chuck. What is the general approach to ensure I drill the 6 holes in exactly the correct spot ?

http://i663.photobucket.com/albums/uu354/topari/DSCN3691Medium.jpg

http://i663.photobucket.com/albums/uu354/topari/DSCN3692Medium.jpg

http://www.shars.com/products/view/994/Adjustable_Universal_Chuck_6quot

TR.

It is not a big job but requires a good deal of accuracy.

Essentially the work is in two parts:

1.
Make a "ring" that is say 1mm less than the chuck bore diameter "D1" (3.125") and that is say 1mm less than "h" (0.689") plus say 4mm to be located in a bore in the backing plate (see later) and that has four or six 1/4"-20-UNC (or M6) HHSC's on a Pitch Circle Diameter of 2.330" to hold the ring into/onto the bore in the backing plate.

The purpose of the "ring" is to provide a "seat" for the six chuck adjusting screws to operate on to adjust the concentricity of the chuck on the backing plate.


2.
Your backing plate needs to be mounted on the lathe (note with "Cam-lock" "pin" goes into which hole in your lathe spindle flange) and take very light facing cuts on the face, outside diameter and the bore. This will "true up" your backing plate to/with the lathe spindle axis and the spindle flange.

The backing plate needs to have sis drilled and tapped 1/4"-29-UNC (or M6) holes on a 5.343" PCD (to suit the chuck holes on PCD "D2") to fasten the chuck to the backing plate when the "set-true" adjustment is complete.

The backing-plate needs to be counter-bored say 5mm deep and accurately sized for the outside diameter of the "ring" at "1." above.

The backing plate thickness is quite OK.

Where do you live in Australia (OZ)?

Is your lathe in the Hare and Forbes (HAFCO) catalogue at:

https://www.machineryhouse.com.au/Bench-Lathes

https://www.machineryhouse.com.au/Centre-Lathes

If you wish you can PM or email me if you think it or I can help.

I am quite happy to answer any questions on the forum as posts in this thread as well as it will come to the attention of a lot of others too who may be interested or who may wish to comment too.

TR
09-21-2010, 07:02 AM
My lathe ...

http://i663.photobucket.com/albums/uu354/topari/DSCN3695Medium.jpg

Located Ferntree Gully.

oldtiffie
09-21-2010, 08:01 AM
Its a small world TR.

I live on the Mornington Peninsula now, but when I was going to Box Hill Tech, Swinburne and during the first two years of my Apprenticeship we lived in Walbundry Avenue - just off Butlers Road (Lower Gully) as it made its way to Jean Street (Upper Gully) - 55 years ago.

I think I've got your lathe:
http://www.machines4u.com.au/view/advert/CENTRE-LATHE-SM-1340A-330MM-1000MM-BEST-PRICES/6451/

http://www.google.com.au/#hl=en&source=hp&q=SM-1340A+lathe&btnG=Google+Search&aq=f&aqi=&aql=&oq=SM-1340A+lathe&gs_rfai=&fp=62a3b4c4a0e828f3

http://www.machines4u.com.au/machinery/51/6451/CENTRE-LATHE-SM-1340A-330MM-1000MM-BEST-PRICES_12403.jpg

Similar to Hare and Forbes?:
https://www.machineryhouse.com.au/Products?stockCode=L179D

https://www.machineryhouse.com.au/images/15104.jpeg

Those 6-jaw chucks are very nice and very accurate indeed. If set up correctly they should relocate to better than 0.0005". They hold thin tubing and delicate stuff very well - the more so if you have soft jaws fitted to them.

Let me know if I can help further - its your call.

Richard-TX
09-21-2010, 09:15 AM
I have that same chuck. I purchased the correct adapter plate from shars. The only thing that I needed were some metric bolts that were unavailable at the hardware store. I would up buying a box of them. PM me if you want some.

franco
09-21-2010, 09:56 AM
Tiffie,


That job is best done on a rotary table.

I am in the middle of making adaptor plates for 80mm chucks and face-plates for my universal grinder.

The process is very simple and very accurate on a rotary table.

From the specification sheet for your 6-jaw chuck: what is the Pitch Circle Diameter?

I could not agree more, BUT

I recently made a back plate for a new Fuerda 160 mm 4 jaw chuck. The drawing showed the PCD as 145 mm and four 10 mm holes for the fasteners. I now have a backplate with 4 spare holes, because when I went to fit the chuck the actual PCD turned out to be 142 mm, and the fasteners were 8 mm.

It pays to check the actual dimensions first!

franco