Emag Battery Pack Bottoms

[luke]

I'm going to make a few EM battery pack bottoms, does anyone need one? As I understand they are in short supply.

They won't be anything fancy or earth shattering just a ULE replacement for the factory part.

[athomas]

When you make them, hollow the bottom out on the inside to make them a bit longer on the inside dimensions. That way, users can use the longer button cells for replacement battery packs without making the battery too tight in the housing. Users having original length packs, can still use a spacer to keep the pack from moving.

[PsychoJester]

How much and are you talking about just the bottom part of the battery holder?

[steve_81]

How much and are you talking about just the bottom part of the battery holder?

Yes, just the small bottom portion of the battery holder PyschoJester. Thanks again Luke for undertaking this project.

[luke]

How much and are you talking about just the bottom part of the battery holder?

Yes, just the bottom.

[Tunaman]

Just be careful. There is exactly ZERO room for error or the bolt heads will be through the wall of the bottom. Been there done this.

[luke]

Just be careful. There is exactly ZERO room for error or the bolt heads will be through the wall of the bottom. Been there done this.

Can you elaborate?

[Bunny]

I would be interested in a few. If I remember correctly, I had about 4-5 times in the re-anodizing process where the bottom piece disappeared and I had to track down another one. I would stick to the original design of the bottom part dovetail and all. I remember the custom milled packs with the dovetail milled off would sometimes cut it too close to the end of the piece. (Hopefully that makes sense) If not, I will get some pictures for comparison.

[knownothingmags]

Just be careful. There is exactly ZERO room for error or the bolt heads will be through the wall of the bottom. Been there done this.

PTP did this a lot,

[steve_81]

It's gotta work, I need one lol

[luke]

I got around to doing some measuring and the thinnest wall that looks like it could be a problem in the anno tank is between the dovetail and the countersink for the bolt head, it's 0.0177". I can fudge that some because the dove tail has no use down there at the bottom.

When I reverse engineered the part years ago, I did the cavity bottoms with a wall thickness of 0.066" which is sufficient. (Per Tunamans comment)
On the other bolt head "countersink wall" the thinnest part is 0.022" cant really fudge that because it wouldn't match the pack.

I wonder if the anno guys are running the tanks with to many amps?

[knownothingmags]

I got around to doing some measuring and the thinnest wall that looks like it could be a problem in the anno tank is between the dovetail and the countersink for the bolt head, it's 0.0177". I can fudge that some because the dove tail has no use down there at the bottom.

When I reverse engineered the part years ago, I did the cavity bottoms with a wall thickness of 0.066" which is sufficient. (Per Tunamans comment)
On the other bolt head "countersink wall" the thinnest part is 0.022" cant really fudge that because it wouldn't match the pack.

I wonder if the anno guys are running the tanks with to many amps?

I would talk to ptp,
they don't make their pack bottoms with the dovetail,
and that one bolt head counter sink has broken through the wall on the ones I have gotten, they have never caused any problems for me.

my 2 cents.

[luke]

I dont recall ever seeing one without the dove tail, does it look OK on the pack?

It would save time if I didn't do the dovetail, I could pass that on to you guys. I want to make these low enough in price that it wouldn't make sense to send one in for ULE milling. That way I can drop that mod service and just sell the new ULE bottoms.

[BLachance75]

I have a PTP battery pack at home I can take a pic of for you. They cut the dovetail off about halfway down the battery case and have a bottom with a flat back.

I found this, shows the cut on the battery pack. I'll take a pic of just the bottom if you want.

[luke]

Here would be the two machining options, either one will fix the problem and cost a little less than the dovetail.

Option 1


Option 2


I vote for option 1.