Enclosed track question?

[Charlieboy]

Hey guys,

I was wondering if anyone knew the procedure for milling an enclosed track out of either a sheet or a rod of UHMW. I want to mill my own tracks and place them into a dovetail, the only problem is I don't know which bit etc. to use in order to get them to fit the dovetail joint. Hopefully I explained myself well. Look forward to your replies... Thanks, Charlie

 

[Tin Man]

Charlie - There are a couple of options. Josh at Neptonics Systems sells bits on his website for cutting enclosed tracks. His bits have a 1/4" diameter "neck", which means that the slot in the top of your track needs to be at least 1/4" wide.

I buy my bits from www.sfscarbide.com. They make custom bits which are a little more expensive, but can be ordered to your exact specifications. I get mine with a smaller 3/16" neck, which I prefer. I like to be able to shoot both 9/32" or 5/16" shafts from the same gun, and a 1/4" wide slot doesn't leave much room to "enclose" a 9/32" shaft. Give them a call and talk to Bob White. Also, you can save money if you make the shank of the bit no larger than needed. So for example, if you are using a milling machine that can accept 3/8" collets, then get your 5/16" bit (slightly oversized for shaft clearance) cut with a 3/8" shank, instead of the larger 1/2" shank that a router would require.

Also, be aware that UHMW can be frustrating to work with. It can be tough to get a clean cut, and there is not an easy way to sand or file it afterwards. It's great track material from an impact and low friction stanpoint. Delrin is much more "user friendly", but heavier.

EDIT - Oops. I went off about ball end cutters for the track, but you asked about dovetails. I'm not sure what the angle on the Neptonics tracks is, but anything commonly available in the 8° to 11° should work fine for the dovetail. The hardest part by far is holding the UHMW to cut it.

 

[Charlieboy]

Thanks,

Yeah my question was more along the lines of near the end of your response. Cutting the dovetail in the track is no big deal. Basically I'm wondering how a company like Neptonics fabricates those UHMW to fit into a pre-milled dovetail track. There's gotta be a router bit or something I could use, I'm just not sure. And I'm sure your right, no matter what bit is available, holding the UHMW is gonna be difficult especially if it's a rod. Also thanks for the info on the ball cutters, I saw one of your other post where you recommend that company. I def plan on doing that and would actually like to get the specs you use so that the track will except both size spears too. I'll probably just order a copy of what your using, sounds like you've already taken all the guess work out of it... Thanks, Charlie

 

[Tin Man]

I have been told second hand that Neptonics cuts them out of a flat sheet on a tablesaw. But I really can't say that for sure.

My dad makes dovetail delrin tracks using a combination of steps. He starts with rod, which he runs through a wood planer to get two flat parallel sides for the top and bottom. Then he has a jig for his mill that allows him to hold the noodly thing while he cuts the sides with a router bit.

 

[Charlieboy]

Definitely got my brain working now, I think I know what I'm gonna do... You da man

 

[Old Man Dave]

Jtkwest (Jason) http://forums.deeperblue.com/members/jtkwest.html has posted a whole load of stuff on router bits for making enclosed tracks. He pours his and machines them when set. This is a good thread http://forums.deeperblue.com/diy-homemade/85671-5-time.html .

Look up his other posts as he has been very into building enclosed track guns. I think he had some neptronics router bits for sale. To do this go to his profile page (link above by his name) and click - statistics - find all threads started by Jtkwest.

Dave.

 

[Charlieboy]

Thanks bud I really appreciate it. I'm always open to more suggestions... Charlie

 

[jtkwest]

Thanks bud I really appreciate it. I'm always open to more suggestions... Charlie

i have got a pair of slightly used neptonics router bits for sale. 40$ for both 9/32 and 5/16 tracks. josh from neptonics told me that he he cuts the ball track groove into sheets of uhmv, then cuts the angles with a table saw. they dont always come out perfect, uhmv is a really difficult material to tool. BTW: the angle on his dove tail bits is not standard. it is less angled than all other dove tail bits i have used. i also have one of those for sale 30$(neptonics dove tail bit) i used it once on the first gun i built. i put a uhmv track in it. it works ok, very little friction. the poured method is better by far. it is more work, but the results are better, unless you are using a plastic muzzle, like daryl wong. which will hold the track in place for you, if not_ the delrin is just sitting in the groove, not really attached. where in florida are you from? is this your first build?

 

[Charlieboy]

Thanks for the info. I'm from New Smyrna Beach, we are just south of Daytona, about 7 hrs north or you. What method do you use for pouring your tracks, I've heard a lot are using fillers etc., what brand product do you prefer? Do you make guns for a living? I am actually going to be in Key West for my wife and I's anniversary, hope the conditions are good. Thanks

 

[jtkwest]

i use 40% milled fiber in my mix. you want it like a thick milkshake, not peanut butter consistency. i like mas brand fiber, but west system will work. i use west system epoxy and graphite. use just a pinch of the graphite, or you will burn up your bits. about 1/4 teaspoon graphite powder per track. when you cut your groove for the track, do it an extra 1/8" deep. then after the epoxy hardens you can run the stockthrough the table saw to cut off that top 1/8" ,(it will contain all the bubbles) that is the easiest way to do it by far. after that, the trigger slot can be cut with a drill press with 1/2"forstner bits, (clean with chisel) the trickiest part, can be the line release slot , in my experience. good luck, keep us posted, we like pics the best. and no i dont make guns for a living. not yet anyway, i'm still practicing. i made 26 guns or something like that, so far. all with poured enclosed tracks, except two. if you are in key west in the next two weeks and you want to shoot some fish, or check out some guns, let me know. i have a boat also. i am in town for two weeks, and i plan on diving most of the time. contact me if you are interested in going out with us