How would you accomplish the following?

[kd5ahl]

Background info:

I want to build a battery pack to go underneath my underwater video camera.

The pack would be made of delrin that is approximately 2.5 inches thick and about 6 inches wide, and about 6 inches deep. I have not finalized the dimensions yet because I am still deciding on battery types. I am leaning towards the M size LiFEPo2 cells that are about 1.5 inches in diameter and around 5 inches long.

What I want to do:

option 1: Bore into the narrow end 1.5 inch holes to slide the batteries down into.

option 2: mill a 2 inch wide slot and build a flat battery pack to slide into it. Like a flat version of the ones Mdocod makes. See below for one half of the holder.

the real kicker is that I want the access to the batteries to be through the narrow dimension of the delrin. which means boring 5-6inches.

I don't have a mill, but I do have a 7x14 lathe. I also have access to a woodworking drill press of dubious accuracy.

I am drawing up some concepts on how I think I can do it and will post them later after I'm done, but I am looking for any suggestions you folks might have.

Kelsey

 

[kd5ahl]

My first option:

Install a plate onto my lathe's cross slike that puts the centerline of the delrin block at the spindle centerline, and clamp the block to the plate for machining.

Then make a endmill holder out of steel rod to allow for a deep enough plunge, and then take it easy on the plunges.

To be honest, this scares me. After seeing mdocod's "zombie killer" in use, I can't imagine plunging a 1.5inch endmill at the end of a 4-5 inch steel rod chucked in the lathe into the delrin block.

Kelsey

 

[jhanko]

How about a 1-1/2" forstner bit and a drill press? They cut plastic very nice and make clean holes...

 

[kd5ahl]

How about a 1-1/2" forstner bit and a drill press? They cut plastic very nice and make clean holes...

that might work. I just wonder how much the bit would wander on a 6" depth of cut.

the more I play around with the modeling of the mdocod style holder in 3D the more I like the idea of separating the battery box and the battery pack into 2 parts.

makes cutting that slot harder though. Any way I look at it the idea of milling a hole that deep is scary to me.

I have a clear polycarbonate housing from Ikelite for my video camera, maybe I should get the battery box injection molded. LOL big $$$!

 

[gadget_lover]

The forstner bits have a round disk that will tend to follow the original hole. combine it with a drill press and you are good to go.

A battery pack will not need a lot of precision, as long as you leave some room for the errors.

I'd do the side-by side, but would not worry about a slot. Chain drilling can do a lot for you here.

Dan

 

[kd5ahl]

forstner bits it is then.

Thanks for the advice!