Rotary table Chuck

[barsam]

Hi all.

Recently I purchased a Parker Daedal rotary table from ebay (photo attached). The plan is to use it as a 4th axis for my cnc router.
As you can see the table is a flat plate with threaded holes at 4" and 5" (Table it self is 6"). My problem is that I can not find any suitable chuck or adapter with chuck that can fit on it and I am pretty convinced that there isn't anything suitable for it out there.
Does any of you have any idea on how can I fit a chuck on the table so that I can use it as 4th axis?

Thank you.

[jalessi]

Make an adapter on a lathe, that is how we made ours.

[kawazuki]

With a bolt on chuck you'd be limited to a 4" chuck as the 5" PCD holes would be needed to bolt down the adapter! If you used a screw on chuck then you are only limited by the stepper motor mount - looks like a 8" chuck is just about do-able?

[DareBee]

You can buy or make the adapter plate.
Bison has them specific for 4th axis mounting.
I use a 4 jaw SCROLL chuck on my 4th so it is real easy to start with square stock if I wish.

[barsam]

Actually I have looked at Bison but I couldn't find anything that can me screwed on my table without modifications.
I am afraid that I will have to find a way to make an adapter. So I will have to find a machinist for that. I live in Greece and some things are very hard to find here and even if you do find them, they are very expensive.
I have a lathe my self but it is a mini one, so I can not do it my self.
Maybe I can order it online. Does any of you know if there are such services online?

Thank you.

[jalessi]

http://www.littlemachineshop.com/pro...Product+Search

[Andre' B]

You want what is known as a front mount plain back chuck.
http://www.btcchuck.com/catalog/frontmount.pdf

Most all chuck manufacturers make them including Bison but they are a bit harder to find, and more expensive.

[DareBee]

http://www.toolmex.com/documentation...atalog2009.pdf
Page 32

[handlewanker]

Hi Barsam, as the man said, you need a chuck with screw holes through the face to bolt onto an adaptor plate, which will probably be 150mm (6") diam to suit your rotary table.

The adaptor plate is thick enough to allow sunk in cap screws to bolt the plate to the rotary table, (they musn't stick out above the adaptor plate face), then you bolt the chuck to the adaptor plate, because it's a good bet the chuck screw hole pitchings wont fit your rotary table screw hole pitches.

The adaptor plate should be drilled and counterebored for capscrews to fit it to the rotary table face, and drilled and tapped to accept both three jaw and four jaw chucks, if you have them, because they will probably have different hole pitches for the mounting bolts.

Make sure the bolts are a good clearance fit through the chuck (.25mm, .010" undersize), as nothing is worse than a chuck that runs out and can't be adjusted.

Even with a spigot back location the three jaw chuck especially wants to have some freedom (about .25mm, or .010") to allow it to be "bumped" into position before tightening down, so that a test round bar will run dead true for rotation when tested with a dial indicator.

The four jaw chuck only has to be checked on the outside rim for true running.

Most important, before bolting down, make sure the mounting faces on the adaptor plate are countersunk both sides around the screw holes, and absolutely deburred around the screw hole area.

If you can only get a chuck(s) that have tapped holes in the back near the rim of the chuck, then just get a bigger diam adaptor plate about 200mm (8") by 15mm (5/8") thick and bolt through from the back.

Whichever way you go the adaptor plate will have to be faced clean before fitting to get rid of the mill scale if using black steel plate.

If you can get a piece of cold rolled or bright mild steel plate, it will be from a flat steel section and will have to be cut round with a bandsaw and turned true.

You could also get the plate burnt round with a plasma or oxy cutter, but it will also have to be faced and turned true.

It must end up dead parallel, most important.
Ian.

[NEATman]

Barsam-
If you are always planning on using this table with a chuck, you could just modify the existing table. It appears to be designed very closely to one that had been produced where I used to work (competitor of parker), so the table can be removed, modified and replaced. Make an index mark on the inside bore of both the hollow shaft and the ID of the table - this is so you will replace it in the same orientation later. If you remove the four screws visible in the center of the table, it should come off easily. It should be a flat disc, so modification should be easy. When you replace the table, indicate off the bore to get it concentric to the bearings by rotating the table with the screws slightly loose, and tap it lightly to center it before tightenig the bolts securely. You can then mount your plain back face mount chuck to the original table, clamp up a piece of drill rod, and indicate it in the same way you indicated in the table.

Keith

[barsam]

First of all I want to thank you all for the help and the precious information you shared with me.

Second, I want to share my thoughts with you regarding the table and the chuck of my rotary table. In fact my thoughts are kind of related to the post of NEATman regarding the modification of the table bed.
Actually I was thinking of replacing the existing table bed with a new one made of aluminum that I will mill on my CNC router. I know that there is great deal that I will have some run outs and that it may not be perfectly round, but I was thinking that I can leave some offset (0.2 mm or so) and re route the bed as it is mounted on the rotary table by rotating the table.
This way I will make it perfectly aligned with the axis of the rotary table. This will also give me the chance to have an alignment center for the chuck on the table.

Attached is a picture of what I have in mind.

Do you think that this can work for me?


Thank you.

[NEATman]

Barsam-
Your approach should work for you if your accuracy requirements aren't really tight.
To make it as accurate as possible, I would suggest that you machine a flat area on the router bed to get it parallel to the travel (qualify the table) first.

Mount the new tabletop to the rotary table and machine the top and the OD & ID (if you care) while the table is rotating, so that the surfaces will be true to the bearings of the rotary table. The only remaining error would be how flat the table top is due to the straightness and flatness of the ways on your router, as a function of how you use the axes on the router to cut the table.

Keith