Canadian Airgun Forum

I'm on vacation, so I'm enjoying some quality time in the workshop. I was making a thing when I realized I was going to need a custom tool for the next step (I needed a hole size that fell between two number drills). So I stopped working on the thing itself and started work on the tool I'd need. But after some ineffective attempts with a dremel, I realised that I needed a tool to make the tool. So I stopped working on the tool for the thing and started working on the tool for the tool. I'm hoping this doesn't go any further or I may never get back to the thing itself, but will have filled the workshop with goodness knows how many bits of one-off junk that will probably never be used again!

Yesterday I cut off a piece of aluminium stock and faced off the two ends with a fly cutter. This morning I drilled a hole through it. All morning. One hole. It reminded me of the discussion about how long Jez takes to make his awesome lever action rifle on this thread

topic65588-15.html

I'm clearly orders of magnitude slower than Jez

Here's a pic of my hole, a rather splendid .760" in diameter in a piece of 1x1.5" bar


I ran drills until the lathe started to stall at 31/64" - it's a very small lathe, and then used boring bars to finish it off. Aluminium chips everywhere

Jim

Keep the chips to melt when you are casting your own replacement parts!

_________________
Keep you powder dry and your seals oiled.
Shoot straight and safe.

http://plinkercases.ca/

always surprizing how much time you can spend on things that seem simple .
so what will it be ?

It's a carrier for the flexible drive shaft of a dremel, so that I can run small grinding wheels on the carriage. Well, I guess you could use any dremel bit, but the grinding wheel is what I have in mind. Then I can hold some round stock stationary in the chuck and hopefully make a very simple reamer. I drilled and tapped a hole for a set screw to hold the head of the drive shaft in place, and drilled the through holes for the mounting screws. I just need to mill out some relief on the underside and it will be ready to try. Need to find something to cover the ways with so the grit from the grinding wheels doesn't get everywhere and cause wear.

Those Dremel/Work Force/Power Fist grinding wheels seem to " particle off " quite fast even at the lowest Dremel speeds. Where they seem to shine is held stationary against something rotating in the drill press...

I've often envisioned something similar to a drill press mount for the dremel. I don't really care for the dremel factory drill press mount~ very spindly looking.

Regards,

Doc Sharptail

_________________
"Ain't no half-way"
-S.R.V.

Well I'm not on vacation... but I am self-employed, which for an airgun enthusiast is a bit of a dangerous situation. If interested in modifying the machinery, that is. So all it took was seeing this thread today and of course I had to launch into a leftover chunk of 1/4" 6061 aluminum sheet and make a barrel band. Something to steady a HiPAC and one extension (whenever they finally get here - why is international mail so SLOW?) against my new 3/4" barrel shroud. Took about 40 minutes on my tiny TAIG lathe with the rough sawn aluminum, then some minutes on the belt sander to shape the outside. Lines up perfectly with the shroud and tube, an easy slip fit. Got called for supper so I had to put off shining it up until after eating, then after a carol singing dessert party with friends...... so I finally got to do that now, at bed time. Dang it. Anyway, here's the thing, ready to get put onto my 2240 when I get the HiPAC installed. I'll take a walk to Home Depot tomorrow and fetch some 8-32 grub screws. Figure if I carve tapers onto 3/8" set screws to sort of match the curve of the barrel shroud and Crosman tube it's a neat solution for solidly anchoring the two, making 4 pressure points with 2 screws, and threading the thickest part of the aluminum. I'll be tinkering for a while yet, but once settled I'll be doing a textured camo paint job, so not too worried about proper polishing.



I'm only counting the dollars spent on actual parts. Not the time. So this will only be a modestly expensive 2240. If I counted my hours, at my job rate... well, let's just say it'd be stupid to do that. No one needs to know, right?

That looks great. Two large holes in 40 minutes?! Man, I have to speed it up

I've often wondered about how to shape the outside of a barrel band, getting bogged down worrying about not having a rotary table and large milling machine to cut the outside curves. Just sticking it on the belt sander is such an obvious solution now that you've said it (where's the face-palm smiley when I need it?)

Doc, I've not noticed the grinding wheels wearing too fast, but I guess I've not really used them that much. The abrasive cut-off wheels really disappear before your eyes, but they are supposed to be consumables. Ah, coming to think of it, some of my small grinding stones have worn badly where I've abused them, so you're right, they're not particularly robust. Ah well, at least cheap replacements are available on ebay. I've wondered about that drill press add-on for the dremel. My main drill press is solid but difficult to get very accurate alignment on small holes, so I normally end up using the lathe instead. That's ok but a bit slow getting setup. A whee dremel drill press might be a nice alternative, but you're right it does look a bit on the spindly side.

Jim

Carrier in position and ready to use

It's a bit marginal, there's an unpleasant amount of play in the bearing in the head of the flex-shaft, and the first grinding wheel I tried tended to jump and grab. The one in the photo worked better. Annoyingly, I have a second flex-shaft which I discounted using because it has an awkward (for this purpose) shaped handle. On closer inspection it seems to have a better bearing, and the handle is easily removed to reveal an ideal cylindrical section of exactly .600". Guess I'll probably be making another mount!

I used it to make this very simple short reamer

I didn't think that through very well, the cutting edges ended up on the anti-clockwise side. Oh well, it did the job, surprisingly well really. I only needed it to shave a little off some holes in a piece of delrin...


Jim

Great pix!
You must be having a great time.
Speak of the devil, I'm carrying the same grinding stone around in a sweater pocket. It got left on the d.p. at work, and I keep forgetting to put it away.

Wonder when Crosman started coding the pellet tins that way? I've got a 2 year old tin of .177 ultra mag heavy here that doesn't have that inking on the lid edge...

..."consumables"

Regards,

Doc Sharptail

_________________
"Ain't no half-way"
-S.R.V.

Nah, speed will get you aluminum for the recycling bin as often as not. But I'm not a hugely patient fellow, especially when playing around when I ought to be working. So I'll often wing it on the lathe. No serious setup, just roughly mark something, start drilling, open out the hole a bit at a time, then start measuring seriously as I get fairly close to where I want things. In this case the whole job is a bit like that. I made a plastic block with a carriage bolt mounted in it to push the 3/4" aluminum tubing through to make way for the HiPAC and the Crosman main tube, a rough sort of forming mandrel, then manually trued the downward-curving aluminum tube to correct for the warp introduced by the mandrel. Faking it, really. But with some nudges here and there and a lick o' paint it'll look good.

As for the belt sander being obvious... well, sure, but it has drawbacks. Certainly a lot of eyeballing going on. And dropping the part into cold water frequently as it gets REALLY hot! But I like my cheap little noisy CT belt sander, garbage though it is as compared to a proper one. Don't use it often but when there's a need it shapes things a lot faster than I could by hand. Just have to remind myself that the speedy removal rate applies to fingers as well, so stay clear.

I think I probably have the same CT sander, with the disk on the side? I never seem to use the disk, so I moved the table to the belt. Shame it didn't come with two tables really, although since I don't use the disk I guess it doesn't really matter. You're right, it sure is noisy.

I didn't understand your description of the plastic block mandrel, which worries me as it sounds like you have a useful technique that I don't know about If you have time, could you possibly run that past me again, maybe with a quick photo if that makes it easier to explain? Is this how you made the two holes in the barrel band, or was this for something else?

Sorry for all the questions, I have this thing about learning new ways of solving problems. The world is full of neat ideas, and there's so little time to discover them!

I know that feeling. Learning stuff is the everyday bonus of which we can take advantage. Sorry I wasn't forthcoming enough in my description. Guess I was feeling guilty for thread-jacking a bit. I'll be posting about it in more detail when I get my 2240 done, adding some pictures to my existing 2240 mod thread. Just waiting for the snail mail to get that HiPAC to be so I can dig in and finish!

The mandrel thing was to form the bottom face of the 3/4" aluminum barrel shroud tube. I made a couple of delrin spacers, one for just ahead of the steel breech and one for part way down the barrel, with the aluminum front cap centering the muzzle. I wanted a long clean line from breech to muzzle, not a skinny looking long barrel. The 3/4" tube worked just right with the breech end counter-sunk to press against the bevelled front edge. But of course with the Crosman steel breech there's no room for the 3/4" tube! So I had to cut it out, I thought initially, sawing all the way down to clear the HiPAC plus an extension. About half the length of the tube. But that job was bugging me. Too hard. Probably slightly messy results as I don't have a mill nor any other obvious way to slot aluminum tubing. Guess I could use a Dremel saw... but that sounded dangerous and noisy and generally obnoxious. So thoughts of alternatives were bubbling around in the back of my mind.

Then it occurred to me one day last week that I could just form that part of the tube, make it concave instead of convex. So I took a short piece and put it in the vise with a dowel inside to maintain round, part of the dowel carved away to allow for compressing that one area. Bashed on it with a ball peen hammer. Made a mess of 4" of tube. So that was a failure. But then I got busier thinking, and the next evening realised I could just make a slippery form with a 3/4" hole in it out of some UHMW polyethylene scrap I picked up at the plastics shop a couple of years ago. It's only 3/4" thick, but perhaps big enough. So I bored a 3/4" hole in it, then a 1/4" hole from one side, then dropped in a round-headed carriage bolt which I turned and polished to match the radius of the Crosman main tube. Popped that in from the inside and snugged it against the hole edge with a nut from the outside. It's offset, about 2/3 of the way through from the side I was going to press into. I braced that against a bench dog and a couple of wooden blocks clamped on each side of the hole, then used my main bench vise (I built a large woodworking bench for myself in about 1988, with two big vises as part of the design - thing weighs quite a lot more than I do) with another bench dog to push the tube right through the plastic mandrel, the relevant path on the tube surface rubbed lightly with moly grease to keep it moving across the steel with no scoring.

The result was a neat, if ever so slightly spiralling groove along the bottom of the tube. I'd found some forum post somewhere, a helpful fellow offering exact measurements beyond the 2240 tube for various configurations of HiPAC parts. So I knew where to stop the groove. I had to push it through again with some twisting pressure on the tube, part way, to get rid of the spiral which ran for several inches. But not a big change. Just something to watch for next time. A bit of sanding to smooth a few shallow wrinkes and it looks almost good, will look good painted. There's slightly more than enough clearance for a thick layer of paint. Should be no problem mounting and un-mounting the HPA parts for maintenance. And when it's all together with a barrel band out near the fill nipple the concave part of the tube should hardly be noticeable. Anyway, done with the long-winded stuff, here's the picture showing the tool and the mounted tube, the groove to vanish behind the HiPAC once it's on there.



Oh, and the holes in the barrel band were just drilled then chased bigger and bigger until done with a hole enlarging 1/4" square shafted tool, the standard one in the TAIG kit but ground so it can handle starting in much smaller holes.

Ah, now I understand - thank you I had exactly that problem with the shroud for my 1377 and took the dremel route. It's pretty much as ugly as you'd expect, even after tidying it up with a file, but fortunately it's hidden by the stock. If I do it again I shall have to try this. Cutting the flat for the carriage bolt to sit on, on the inside of the 3/4" hole must have been tricky?

Excellent creativity there Gerald. A simple tool for a complex shape building...

_________________
May the cry of the pack be with you upon your hunt

Whitewolf

No flat. UHMW is squishy. If I were doing this again I'd probably bolt two layers together thoroughly (or actually go out and find a fatter block of the stuff) to help maintain round better. The bolt head just pressed into the plastic with tightening of the nut, so it was a matter of stopping when the protrusion was just right for the channel I wanted.

Simple, sure, but problematic. Forgot to mention the curving of the tube. The force on one side caused the tube to arc, about 3/8" or so for the foot-long depression. So I had to gently tweak it back straight. After doing this and getting it satisfactorily true I stumbled upon a fellow doing it right in another forum, with larger tubes he uses for integral suppressors on airguns:
http://www.airgunadvice.net/viewtopic.p ... sc&start=0
Guy's serious. But then again he's doing a bunch of these things professionally.