Boring proceedure

[Roy]

Well I think I am going to go with an electric powered feed for my BP X axis. I got some drawings for the Servo brand that would bolt directly to my machine without having to remachine my leadscrew, and from what I can tell it includes a casting that takes the place of the original flange mounted gearbox (upper half) and provides a mounting for a new bearing that fits on the leadscrew in place of the original tube / bearing assembly, and extends out to where the original unit ends, with a flat surface to where you can mount the drives without the flange that bolts to the table end.
So it seems all I need to do is make a casting, and some spacers to fit up a drive. So needing to bore this csating that I intend to cast, out of aluminum, or ppossibly machine it out of a block of aluminum I have, what would be the best way to obtain the bore for the leadscrew to pass though and retain the bearing. The casting is basically in the shape of an "L" with the lower portion of the L bolting to the table end. The bearing and leadscrew passes though the backside of this laid down L casting. I can cast it with semi finished bore using a core, or make a typical journal cap like on a crankshaft main bearing and bolt it fast and bore it and the casting or block of aluminum seperately. Any advantage to it being all one casting as opposed to having a journal cap? All it will support is the end of the lead screw / bearing at the table end, and the drive supports the extra 10" length this leadscrew has........any suggestons appreciated.

I used the mill for about 30 minutes today and it was tough, My old joints sure do not like repetitious movements without locking up and sounding like they are full of swarf!

[Greg_S]

Hello Roy,
Just for the sake of discussion, there is a gunsmith here in town that when faced with the same problem you've had with your old power feed, he made the piece taking up the space that represented the old style power feed casting out of wood. I'm not kidding, I'll bet it's been that way ten years now and he still uses it that way. I think persimmon is the hard wood of choice. I know our tool and cutter grinder man uses plenty of it for special one off grinding fixtures himself.

I know it's of no value but I just thought I'd share that oddity with you.
Greg

[Roy]

Persimmon is some good hard wood that is pretty darn stable. It grows wild around here. I thought about that same thing while I was working on my pattern for this piece. I said to my self, too bad you can't utilize the pattern instead of having to basically make the item two times........I think its pretty ingenious myself for that gunsmith to do that...........heck a new type drive is only about 15 pounds of so, and other than knowing its wood it should work just fine......Servo is the only manufacturer that makes this piece for this type machine, and they are very proud of it. Push come to shove it could easily be fasioned from structural steel and a little ingenuitiy, but I am taking the cast my own route. Now I just have to make a decision on brand of drive to go with.

Maybe someone knows the answer to this, but I have seen many sites list a drive called the Dynamo Servo drive, and state its made by Servo. Its about /2 the cost of a Servo drive, and other than color looks just about identical. Servo (now bought out and owned by High Quality Tools) has no mention of this Dynamo drive, but the various dealers have it listed as being made for Servo and its identical to their higher dollar drive, with the exception its made in China as compared to the USA........

Another drive I have found being sold is ASONG brand....specifically the AS250..........Heard ALIGN brand was very very good and much cheaper, but have yet to find a place to buy or check them out......

[mm NE Iowa]

Roy,

I have had an ASONG brand power knee on my BP for several years. Other than having to make a spacer to mount it originally, there have been no problems.

It actually came from Harbor Freight and has the Central Machinery sticker on it. -- mm

[Rwilliams]

The Servo brand power feed is about as good as they get for a Bridgeport. Quite often the tool companies will have them on special if you watch their sales catalogs. In fact, Bridgeport stopped making their own power feed units and began installing Servo units on their mills several years ago. They found that the Servo unit was equal to their porduct and cheaper to install at the factory.

The Servo power feed unit is offered in two amperage draw sizes. The heavier amp draw unit is slightly more powerful and will probably work better in a heavy duty shop situation. The lighter amp draw unit is less expensive and seems to be working just fine on my Bridgeport. The installation is very easy and the directions easy to read and understand.

[timekiller]

Hello Roy,
Why are you worried about cutting the mill screw off?

The mill table is pulled or pushed from the left end of the table (the end with double bearings). The right end of the screw floats in a bearing no axial load, only radial forces. And is a slip fit.

Is the screw on your mill too large to fit through the head stock of your lathe? If not I think I have the spec for a mill screw.

We modified mill screws regularly in the rebuild shop I worked in. Purchashing was always getting the wrong screw or else it was cheaper to buy the long ones and have us machine to fit the current mill in the shop.

We even shortened new ball screw assemblies. Those were just harder on the outside.

Ray [img]/ubb/images/graemlins/cool.gif"%20alt="[/img]

[Roy]

Timekiller.......ya know I wondered about that. A mill is usually found in a machine shop, or odds are a person with a mill wold probably have access to or know of a person with a lathe........I would assume if its doable those shops / people would cut their leadscrew, but then I see the stuff by servo with mention of mills with the mechanical gear drive, and its much more expensive due to the leadscrew........thats installed on them... I really don't know. I just was not about to take my leadscrew out, and cut it off, (lathe is capable as to spindle bore) and then have to hunt down a machine shop to mill the keyways etc for the handle assembly etc, and in the process screw it up. Wife is already on me hot and heavy with all the so called good mechanical drives I had bought and had to send back and eat shiping etc on, so I just figured my best alternative was made the same type of casting that Servo has in the drive kit they make for the mill and beg borrow and steal the money to order a ASONG or ALIGN drive......I seriously am open to all suggestions though.

The attached image is of the casting / mount they supply with this mills drive kit. It also includes some spacers and such and a new bearing that supports the portion of the lead screw at the table end, and the drive supports the remaining portion of the screw. The kit eliminates the double bearings on the hollow sleeve as well.

[Roy]

Heres the image, somehbow I must have screwed up on the previous post.