Rotating spindle

[rhfurniture]

I am wondering if anyone has tried making a router/spindle bracket that can be rotated through 90deg manually, so it can be used as a horizontal boring/machining head.
I was thinking of hinging it along the bottom of the Z assembly.

Any experience or pointers would be most welcome.

R.

[mikejohn]

I was thinking along these lines also.
A limitation will be the radius of the router(spindle) limiting the amount of Z movement.
I also am interested if anyone has done this.
................Mike

[rhfurniture]

I have a bosch router which is pretty neat. It sits in a plastic sleeve in the ally cast bracket, which could all be neatened up in the process. It would need a platform on the bed reducing machinable thickness from 6inch to 3.5inch.
My current thinking is 2 8mm plates hinged at the bottom, bolted together for the upright position and with a dirty great aluminium block to bolt into the open "hinge" for the horizontal position. But I know not how to form the hinge and would rather something a bit neater than the block.

R.

[mikejohn]

I've been thinking about it during the day
A metabo die grinder, as Gerald used for a long time, has a small 'girth'.
It also has a long 'nose' allowing clamping close to the body, and again close to the collet.
My Metabo big router sits on a right angled bracket. It occured to me if I could mount the die grinder underneath this bracket, I would have almost a full 150mm (6") of Z movement.
Also, it might be possible to bore in the x direction, or flip 90 degrees and bore in the y direction.
Anyone doing this?
...................Mike

[rhfurniture]

Mike, This is my current arrangement with a cheapo trend 1/4" router. Works very well but I'm limited to 750mm length of whatever I am working on. (I have a benchtop)

r.

191

[mziegler]

How about using a 3/8 inch angle air drill. It is much smaller and thus can drill in very tight places. Mark

[rhfurniture]

My main uses are for round end tenonning (need more power) and machining/boring the tops of chair legs (need more length)

R.

[Brady Watson]

I always thought that a small indexing/dividing head would be ideal for this application. You could mount the indexing head (they have low-profile ones) to the Z-axis, and then mount the router to the face of it. Just about all of them have accurate scales on them and a little crank handle that would let you accurately dial the router from 0 to 90° and anywhere in between. Whether or not this will work on your PRT or not using the stock Z-axis arrangement...I don't know.

I was thinking of something along the lines of this (http://www.grizzly.com/products/item.cfm?itemnumber=H5685&viewtype=images&) but maybe something a little bit lighter in weight.

-Brady

[rhfurniture]

Brady:
Yes, I can see that (perhaps a thinner one, without micrometer, stepped at 5 deg) mounted between the motor and the Z assembly. The main requirement would be that it can be bolted up dead rigid.
Then, would it be sensible, has it been tried, what are the pro's/cons, what is the best way to do it, of rotating the whole Z assembly 90 deg so that (in the above pic) it is mounted towards the camera? I guess a couple of bits of channel across would do it.
Has anyone tried it?

R.

[Brady Watson]

rh,
A rotary table by design is very rigid...It is made for metalworking. I bet that it would be possible to machine 2X .500 aluminum discs with a bolt in the center, mating race and thrust bearing and make one with acceptible rigidity...However, you'll lose the elegance and repeatability of a true rotary table because it has (typically) a 72:1 ratio gear in it and handy crank on it with scale.

The T-rail itself on the Z-axis may also need beefing up since it wasn't really designed to have that type of load on it.

-Brady

[rhfurniture]

Hi,
I now have a different application that could use a rotary head - machining seriously large round tables. I have looked at the shobot indexer on their website and reckon it is set up strictly as a router lathe. I am thinking more along the lines of:
http://www.sherline.com/images/3700cncpic.jpg
And wondering what sort of stepper motor I could attach to run off a shopbot auxiliary axis. Has anyone had any experience of this sherline stuff - is it well made?

R.

ps how long before shopbots appear here:
http://www.owwm.com/default.asp
(I've spent hours on this site)

[Brady Watson]

What do you consider 'seriously large' and how many of these 'seriously large' tables do you think you are going to do in a year? How will the weight of the material be supported if there is no spoilboard under it, just the rotary table?

On a 3-axis CNC machine, a vertical 4th axis is pretty much a waste of money...unless you turn it 90° and use it as an indexer. The Sherline products are good for hobbiests, but lack the beef and size you are looking for, even for indexing applications.

-Brady

[rhfurniture]

Brady,
The size is 1350 dia, but not a regular circle (it is slightly star shaped). I guess I could build a 60" square machine, but the quantity is uncertain and I have no space.
The big industrial rotary tables are serious money and I came across this sherline stuff and just wondered what they were like. I will probably build a spinning table and "index" it manually.

Thanks for warning me off sherline.

R.

[gerald_d]

I must be missing something......why can't the large table be clamped to the SB table and then use good old x,y moves to move the cutter around the table? Why do you want to rotate the workpiece?

[rhfurniture]

1350 diameter needs a 1500 machine to do it in one.
Actually I have an 800 x 800 benchtop. By design the router cutter itself is clear (just) in Y of vertical shopbot pillars, so it should work. I would do it in bits and reassemble but the customer is supplying foam cored carbon fibre blanks that I must lip, shape, pocket and veneer.

R.

[Brady Watson]

Ouch...that's going to be a challenge on a benchtop even using the method that you are describing. If I were doing it, and I couldn't sub it out, I would be inclined to make templates on the benchtop that fit together and then use a hand router to cut out the shape and work the edge of the table.

Heck, the way you are describing it, the benchtop will just be a glorified overarm router. If you were feeling crafty you could use a lazy-susan to pivot the center of the blank, and 4 roller stands set at 9,12,3,6 to support the outside of the table's weight. The only thing is making sure that the table is well adhered to the lazy susan before cutting...and that the setup is REALLY solid (so nothing walks out on you while cutting). Also, when cutting make sure that you rotate your blank clockwise to get a conventional machining direction...

-Brady

[rhfurniture]

Actually I like a challange.
I've done linear indexing most successfully to do long stuff. Even did curvilinear indexing once to make a C shaped wall top for an office reception desk.
The centre will be on my 800mm sq worktop, and I've seriously beefed up the Y carriage so it should work fine - remember I'm after a star shape, so I cannot just spin it.

R.

[gerald_d]

Hang your benchtop from the ceiling - that will free up table space.