Inside Doc's Machine Shop

[DocsMachine]

While I kinda hate to throw in a 'commercial break' here, I should point out I have a Patreon, specifically for the machine shop. It doesn't have much unique content yet, but I'm planning to start a fun paintball project to do on the side- something I've been wanting to do for literally almost 20 years. That will be Patrons-only 'til it's finished, after which I'll post videos to the public. You'll get to see it happen maybe as much a year before anyone else.

And, it's worth noting that, thanks to the Covid lockdowns and the following economic issues, my comic Patreon is literally the only reason I managed to keep the doors open and most of the lights on. The regular income was also the only way I could justify borrowing the money to buy those CNCs.

If you can stand to sign up to toss a buck or three my way through either of those, I'd greatly appreciate it.

Thank you!
Doc.

[minimag03]

done, paintball needs its Doc!

[DocsMachine]

Much appreciated!
Doc.

[Sdawg]

Any chance of PGP fast changers in the future? Or a RVA?

[1snowridr]

After some other fiddling around, including finding out my lathe rather desperately needs a good servicing, I was able to get back to these. It took more hand-fitting than I'd hoped, but after deburring, the occasional bit of filing, some additional boring, and just miscellaneous fettling, I got each part both cleaned up, and fitted into "pairs"



These I took in the house and scrubbed thoroughly with hot water and soap (no pic, you people have seen a sink full of hot water before ) all while trying to keep each "pair" together. That way the bores and ODs of each one match as best as they can be- there's always minor manufacturing differences.

Once they were good and dry, back in the shop I dolloped each one with a dab of red Loctite, and snugged each pair together with a wrench.



Things like this, by-the-by, are the only times you should use red Loctite in a paintball... well, anything. When there is absolutely no reason for it to ever come apart.

In this case, there's no reason for the two halves to come apart, pretty much ever. Really, something like this should have been made in one piece, I only did it this way to try and re-use otherwise scrapped parts.

Once everything- including the ones I'd made earlier this summer- were cleaned up, scrubbed, deburred, fitted and Loctited, I had 20 backs. One's already threaded to 'Cocker, the other 19 are blank.



And, once those had a few hours to cure, I turned the OD down to a consistent diameter:



And there we go, a fair handful of specialty Freak backs, that retain the insert from sliding out of the breech.



These are now available for anyone who needs this style, cut to fit, by order. Let me know what you need it to fit, and if I have one on hand, or have the measurements on hand, I'll cut it and send it off. I'm also planning hopefully at least two more batches of black anno before the end of the month, so if you want them done, just let me know and I can add them in. Or, of course, you can have it plain so you can get it match annoed to your gun.

Due to all the handwork involved, and the low numbers, these will be $120 each, including threading to fit your gun. Add $10 for anno, if I can get it thrown in with the batches I'm already setting up.

I can also set you up with custom tips, with or without porting, and so on.

(As a reminder- this specific lot is for these "retained insert" barrel backs. If you want a back for something that can take a conventional one- 'Cocker, Shocker, Ion, ICD, Angel, etc.- I also have those, and for less than the cost of these handmade beauties. )

If you're interested, let me know by the usual PM, email, smoke signals, carrier pigeon, or AOL Instant Messenger, if you have access to a time machine, and can convince teenaged me to actually get AIM.

Doc.

Hey Doc, One of my struggles is finding something like this that can fit the Palmers Pyre. The pump handle conflicts with the diameter of anything larger than a stock Palmers barrel. Would you have any solutions?

[DocsMachine]

Both are on the list!

Doc.

[DocsMachine]

Hey Doc, One of my struggles is finding something like this that can fit the Palmers Pyre. The pump handle conflicts with the diameter of anything larger than a stock Palmers barrel. Would you have any solutions?

-I've seen several custom Pyres with Freak or other 2-piece barrels. I'd say the easiest solution is to either mill the pump for the necessary clearance, or have a new pump made that fits.

Doc.

[Funsi00]

Stock PPS pump handles either version. With or without s rod have very little material to mill away before exposing the center guide rod.

[DocsMachine]

Quick look at one of today's jobs: I started on a number of small batches of parts back in late September/early October, and have at least started a couple hundred pieces.

The holidays were a bit of an impediment to progress (that and leftovers ) and I've had more than a few other things to do as well- including end-of-year stuff like starting to prep for taxes and the like. So things haven't moved along quite as fast as I'd like- when has it ever?- but at least I'm still makin' progress.

I've had a ton of Freak backs in the works- classics, XLs and even more Bulls- which is the majority of those parts, and I've been needing to get the tooling set up in the CNC and start throwin' some chips. Today I picked an easy one- SI Bushmaster- and, in one of those small wins we all need every now and then, I wrote the program for it, turned the first part, adjusted the tool offset a whopping .003", ran the same part again... and it was perfect. I ran 35 parts with no scrap.

Hey, I'll take my wins where I can get em.







Doc.

[CUBE]

It's so nice to return to paintball and see that Doc is still around. Keep it up!

Used to have a splatmaster, not sure what happened to it. This thread makes me want another one.

[DocsMachine]

Ultra-Double-Top-Secret Thingamabob in the works!



No hints from the audience, please, this is classified information, y'know. I wouldn't want to see it wind up in the internet or something.

No ETA yet, I gotta buy some tooling first, and funds are tight at the moment.

Doc.

[Chuck E Ducky]

❤️❤️❤️❤️❤️

[Jordan]

Ooooo, new and improved RapidReplacers™?

[JeeperCreeper]

I'll take lots of these

[DocsMachine]

Shop Pic O' The Day #1!





Doc.

[DocsMachine]

Part one of what will likely prove to be a comparatively complex part. Not complex in and of itself- like it has a tiny V12 engine in it or something, but rather complex to make. And, to clarify that even further, to make automatically, as in to program a limited-capability gang-tool CNC turning center to make.

I've only ever used up to five tools for one part before, this one's going to take six or seven- and I may have to make a couple of those.

So, first off, I need a collet. The one 7/8" collet I have is a cheap import, and as most of those are, they're ground spot on spec- 0.875". My bar stock, however, is slightly oversized, measuring 0.877". In this setup, I want to start using a bar puller- let the robot do the work -so the bar needs to slide fairly easily in the collet.

For just this sort of thing, they make what are commonly referred to as "emergency" collets- unhardened ones you're meant to machine to size or shape. Longtime readers will know I'm a big fan of the 5C collet- four of my lathes take them, and I have over a hundred floating about the shop- so what I do is periodically pick up a handful of used (partially machined) 'emergency' collets off of eBay, often for a few cents on the dollar.

I picked one of these out of my stash, and set it up in the Sheldon lathe, like so:



For those of you that haven't used such things before, there's three little pins at each of the "slices", so you can tighten the collet in place, and are still clear to bore the center out to whatever size you need.

After a little careful drilling- it's in effect an interrupted cut- and some even carefuler boring, I got it opened up to right at 0.8775".



That gave me a snug, but smooth-sliding fit to the bar stock.



Now, here's where we start running into trouble. In a "real" machine shop, using "real" machines, we'd have a bar-feeder on this turning center, that could feed a full-length (12 foot in this case) bar into the machine at intervals. Turn, part, feed; turn, part, feed; turn, part, feed, ad nauseum.

I don't have a bar feeder. I don't have the room in the shop (they can be 20 feet long) I don't have the money for one (a well-used one in need of repair can be $5,000- the one made by the maker of my lathe is ten thousand) and most often, it'd be a waste if I'm just making 20 or 30 parts anyway.

I do have that bar puller I mentioned, though, and have been looking forward for a chance to use it. But, there's a limit to how long I can leave the bar. I tried cutting off a 36" piece, and it sticks out the back of the machine over a foot:



Now, that's 7/8" stock, and shouldn't "whip" too much. I also fabbed up a delrin collar- you can barely see it under there- to help keep the bar centered as much as possible, 'til the bar works its way into the spindle. BUT... that's an awful lot of stickout, if I'm gonna turn that thing at over 3,000 RPM. I'm going to have to do a little testing to see how safe or stable it is- if that bar bends, it could cause considerable damage.

The other issue- common to many gang-tooled machines- is the stock doesn't clear the tooling table.



I'm going to have to have the cutter extended out quite a ways- which risks chatter- and hope that once it's reduced in size a little, I can get the parting tool- shown above- to it. Else I may have to make an extended holder for that...

None of this is unsolvable, of course, and those of you that work in professional machine shops deal with this kind of thing regularly. But this limited machine, and my even more limited frayed-and-multiply-knotted shoestring budget, make it a bit more of a challenge.

Stand by, more to come.

Doc.

[superman]

Could you make an extended block to help support the boring bar to keep it from chattering?

as far as the bar feeder portion. I want to say I have seen some people use 2 bearings in a v shaped holder on an adjustable stand to help instead of using a full feeder.

[DocsMachine]

What I've been thinking about with the 'boring' bar (gang tooled machines basically have to use bar style cutters) is getting a larger 3/4" diameter one. I'd have to surface-grind a flat on the bottom (towards the tooling plate) to get the cutter back to center, and make a matching tool block that basically straddles the bar.

That'd give me a touch more rigidity, without having to make an entirely new tool or holder.

The two-roller supports are for slower speeds. I'd need something to control "whip" at higher speeds- at least, comparatively, for this machine. Which means three rollers, to give full control of the bar. I've been running most of my parts around 3,200 RPM, and I'm not at all sure how that much stick-out will react. I wouldn't mind it on the smaller machines, since they top at at only about 1,400 RPM.

There is no way, for example, I'd run 1/2" aluminum at 3K with that much stickout- you could almost guarantee it'd whip and crash.

7/8"is far more rigid though, and if not allowed to get too far off center (hence the delrin collar) hopefully shouldn't be an issue.

All that said, though, I'm still toying with the idea of falling back to the old tried-and-true technique of cutting the stock up into individual blanks. Much as I'd like to automate as much of this process as I can, it's looking like I'd either have to spend several days making custom tooling- and blow about $500 on a knurling tool- or set it up to do two ops like I usually do.

Doc.

[DocsMachine]

After much pondering and cogitation, the unfortunate fact is that, right now, I have way too much on my plates, and so at the moment, the top priority is time. Once it's up and running, the per-part time using the bar puller and whatnot, would be lower, and with less labor, but considering I may need to make two nontrivial tools, spend at least another $500 on tooling, and learn how to program and run no less than three different tools I've never used on a CNC (tapping head, knurling tool and bar-puller) the time from now 'til I have a binful of ready parts, would probably be considerably longer.

So for the time being, I'm going to fall back to the tried-and-true method of using individual blanks. Not as quick per part, but the overall process will take less time. As such, I took one of my short bars of material, and as per established protocol, lopped it into roughly equal chunks in the bandsaw:



Also as per established procedure, each one then got faced and lightly deburred on one end, in the (manual) lathe. This, of course, is our reference face.



That one section, for the time being, produced a nice even 20 pieces...



Which will be more than enough to get the first end programmed and turned. My tap holders should be in tomorrow (dang it, I shoulda ordered some gun taps!) and I'll need to dig through the manual, as well as some online sources, on programming and using a tap holder on this machine.

Hopefully I won't break too many of them.

Doc.

[appleguy]

This deliberation reminds me of this XKCD


I have an inclination to efficiency, so the idea of automating a routine task is very appealing to me. More often than not, I just end up overcomplicating the initial project. And if the 'automating' process involves building something (in my case, usually software) I now have a new thing to maintain....

IMO, it seems like you picked the right path for now!

[DocsMachine]

Under other circumstances (I was going to say "normal" circumstances, but for me, this IS 'normal' ) I'd love to get this properly sorted out. This is the kind of thing machines like this were made for- automatically making parts while you stand there sipping coffee and twiddling whatever appendage falls most readily to hand.

But, I'm also very much in the early stages of learning these kinds of esoteric secrets, and unfortunately have no experienced mentor full of hard-won wisdom to back me up. So between that and the various deadlines, overdue projects and of course my patrol of Gotham each night, my free time right now is extremely limited. Meaning that, at least for the time being, I need to get as much done, per unit of time, as possible, with most other concerns being secondary.

Doc.