Friday, May 09, 2014

Multipart assembly.

The feed ramp is a separate piece. The barrel appears to be flanged at the rear, with the locking block slid over it from the front.

The locking block appears to be MIM. The feed ramp looks like it might be pinned in place?

Molded-in logo and caliber designation.
Three shots of the three-piece barrel assembly on the Walther PPX. I can tell I'm going to get a lot of use out of this new (to me) macro lens. I find it interesting that the feed ramp is a separate insert but the locking shoulder is just the MIM block. My initial instinct is that Joe Gunowner isn't likely to take a Dremel to the locking shoulder, but any materials engineers in the audience are encouraged to speculate. (Anyone who just wants to chime in with "MIM bad! Hurr-hurr!" is welcome to go do so at cletusgunforum.com.)

What I find interesting about the gun is that it's obviously designed to be inexpensive to manufacture, but at the same time be serviceable as a duty sidearm. By that I mean that there are plenty of "Ring Of Fire" zinc blasters that are designed to be cheap, but are obviously not designed with an eye toward ruggedness and reliability, whereas this does not appear to exude that vibe; witness the steel slide and slick Mec-Gar mags. Maybe it's a legacy of the volkspistole projects at the end of WW2, but the postwar Germans have been leaders in finding ways to make inexpensive-yet-reliable handguns, from HK's pioneering of polymer frames to Sauer's making slides out of heavy-gauge stampings...

33 comments:

pdb said...

This reminds me a lot of the design and construction of the Ruger American, which is cheap where it can be in an intelligent way that doesn't hinder function or reliability.

Tam said...

pdb,

Ruger is the American master of this. Their revered .22 pistol, the gun that made the company, is a glorified closed-bolt Sten gun with fancy stocks.

Blackwing1 said...

Nice pictures! That new lens does a great job for presenting close-ups of parts like this. Lit with ambient (sunshine) light, it would appear.

Seems to me that the locking block has NOT been polished, and that the polishing of just the feed ramp is a way to save on the machine time. They're polishing only the little part that counts. It also appears that the locking block itself is pinned to the barrel.

I wonder if their intent was also to allow users to customize their feed ramps (that Dremel tool again) without totally destroying the barrel and locking block. Mess it up, all you have to do to fix it back to factory-spec is drive out the pin, replace the ramp part, put the pin back in, and you're good to go.

Even if the MIM locking block doesn't hold up to 5,000 rounds of use, it would appear that this little sub-part might also be removeable (although pins are evident in the second picture, I can't see them in the third). Maybe it's not replaceable, and once those pins are driven in from the left-hand side they're in forever.

It will be interesting to see how this holds up to extensive use.

Tam said...

I haven't talked to anybody at Walther (yet) but I'm betting that the barrel and feed ramp are machined from forgings, the locking block is MIM, and somehow swaged, brazed, threaded, or welded to the barrel, with the feed ramp then permanently affixed to the assembly.

This is, of course, spitballing. :)

Alien said...

It looks like three big well-fitteed pieces, held together by fit and secured with applied tension from the final bit being pinned; I'd guess the pinned ramp, pressing against the barrel flange holds the block in place.

Which is pretty clever engineering, despite being dependent upon CNC-produced and MIM precision fits, and indicative of an understanding of what wears or breaks and is due periodic replacement. It might be interesting to apply a tiny mark to the barrel and see if there's any rotation over thousands of rounds.

The real test is whether or not the individual pieces are available only to the Walther elves or can easily be had by anyone. Anything else in the gun similarly designed?

Anonymous said...

Nothing wrong with making things inexpensively, it's what keeps good engineers in business. It's the making of product what will not survive the the duty cycle + a safety margin because you did not understand the limitations but was dirt cheap that's sad.

It's been a while since I was a metallurgical engineer and kept up on these things, but there's intrinsically nothing wrong with powder metallurgy: properly designed spec'ed and understood.

With proper design MIM parts can be strong & tough enough and significantly cheaper than carving out part from a hunk of steel - MOST of the time. But like any technology , if you use it wrong, like do a 1:1 substitution into a "hunk of steel design" without redesign you are asking for major trouble.



Angus McThag said...

What is the bar the locking block is engaging made from?

I'd guess that the ramp is hardened past where you can take the MIM of the block to keep rounds from wearing it down with unseemly speed where the pin/bar that engages the block is made from something that doesn't wear hard against each other.

I get/don't get the hatred of MIM. It was used where it shouldn't have been and when it wasn't a very mature tech. I'm pretty sure those things aren't true any more.

Farm.Dad said...

Thanks for the Pics. Ill scratch the PPQ off my list . Not because of mim parts , but because I don't like the looks of or trust the long term durability of that assembly . IMO less fiddly parts affixed to each other is better. I could well be wrong on my distrust of their system , but only time will tell .

Caleb said...

Farm Dad, that's a PPX, not a PPQ.

Farm.Dad said...

I set Corrected .

Noah said...

That funky backstrap angle business bothers me, but I'm just looking at it. How does it actually feel? (Understanding that this is entirely subjective - I'm just curious.)

Joseph said...

What's the deal with the X-Men logo on the locking block? Perhaps it a leftover R&D piece from Xavier's lab, everyone knows MIM parts are Magneto's kryptonite.

og said...

Actually, this is kinda brilliant. The issue with feed ramps is that they have to be resistant to a process called "Stiction", which is what happens when dissimilar materials come into contact (Such as the nose of a copper or lead bullet being run into the feed ramp) and there is that tiny moment when they "Weld" together at a molecular level. Most of the time, the force of the spring and the speed of the action are enough to overcome this but sometimes not. And it is possible to have a metal be machined and hardened to a point where this will not happen, but then the hardening and the metallurgy is inconsistent with the desired properties for a pistol barrel. So until this point, everything has been a compromise. This allows the feed ramp to be a metal perfectly suited to it's purpose, the barrel to be a metal perfectly suited to it's purpose, and the locking lug to be perfectly suited to its purpose. I think I like this very much indeed.

og said...

P.S. one of my customers who does large scale MIM stuff says there is a really good possibility that the barrel and feed ramp are injected in place and the sintering process bonds them together, which makes sense.

Tam said...

Noah,

"That funky backstrap angle business bothers me, but I'm just looking at it. How does it actually feel?"

Surprisingly normal. I'll get a picture that shows why (it makes perfect sense when you actually see it clenched in someone's paw.)

Anonymous said...


"there is a really good possibility that the barrel and feed ramp are injected in place and the sintering process bonds them together"

Og: I was thinking the same thing.

tailwind said...

I think Og and Anonymous are on the right track regarding barrel/locking block/feed ramp manufacture.

Doing any further machining, etc on the thing kind of defeats the purpose of using MIM to begin with.

og said...

I'm really looking forward to the t&e on this. It has the hallmarks of a well thought out design, and if I can get my improperly scaled hands to fit around one it might just be a nice carry piece.

Old NFO said...

You answered (possibly) my question on assembly... I'd 'hope' the barrel is welded not swaged on...

Tam said...

Old NFO,

I believe Og and Tailwind have the right of it upthread. Injection-molding the block with the barrel and ramp in place and then sintering would have the desired effect of locking everything together solidly and requiring an absolute minimum of finishing.

Will said...

I suspect that the temps required for the sintering in place would cause problems with the barrel. From the looks of the block, my first choice would be a cold barrel, hot block, and a press/glue fit.

What appear to be two pins in the side depression, may not be. Very "awkward" position to align with the barrel. Not a good location versus the chamber. May be injection ports. If they are pins, I would say the barrel has circumferential grooves to avoid having to rotationally align the barrel to line up matching pin holes.

Even if they are assembly pins, I would expect the parts to not be available to the public. To much potential for poor workmanship at the shop/retail level to compromise the good name of the maker, and not much cost/profit differential to justify selling separate pieces.

tailwind said...

Will,

The pin-like markings on the the locking block are most likely from the ejection pins used in the MIM process. The part has to come out of the mold somehow.

Interesting thoughts on the MIM temperatures and effect on the barrel steel. Perhaps they use some sort of post-injection tempering process.

The Walther website mentions that they have patents on this thing, but I couldn't find any relevant patents or applications at the USPTO. But, they might not be published yet. Could be just Foreign patents at this point, but most European patentees also file US applications when the product is sold in the US.

og said...

Gears and other parts are sintered in furnaces. Most components like this are sintered by induction, which generates enough heat to sinter the metal particles while leaving the rest of the material cool. The process takes a half a second. You could probably hold onto the barrel while the block was being sintered. Yes, I would imagine the divots in the side of the block are for barrel alignment. If one of the components of the binder metal was bronze, the part would effectively be continuously brazed to the barrel, which would be very strong indeed. All of which impresses me a good deal, if that is in fact how it's done. Sooner or later someone will buy one and slice it in half so we can all see.

og said...

This is a demonstration of how induction sintering works. Turns a part that you could crush in your fist into a functioning part in a second.

http://youtu.be/ikScAnPHTUQ

Anonymous said...

I'm guessing MIM block and feed ramp, soldered after barrel assembly.

Sintering temps might distort the barrel. It could work, depending on the alloys being used, but with a good design, soldering the ramp in place would work just as well. The solder would soak into the slightly porous surface of the block and ramp, creating some degree of interdigitation. This would yield a solid lock between the components and solder.

Kristophr said...

I'm not sure it is even possible to put shit in backwards or upside down with a John Browning ( PBUH ) designed weapon.

( assumes lotus position,and starts disassembling and reassembling a 1911 while meditating )

Buzz said...

What the Sam Hill is going on here?
I thought Tam mocked Hi-Point owners?

Tam said...

I do mock Hi-Points.

I'm not at all fond of zinc-slide blowback guns.

Daniel Watters said...

You may trust Walther's engineers, but I really don't place the same level of faith in their superiors at Umarex.

Tam said...

Daniel,

The gun is steel, not zinc, and from Ulm, not Arnsberg. Make of that what you will.

Daniel Watters said...

Here is the US patent application for the barrel:

https://www.google.com/patents/US20130061501

Click on the inventors Wulf-Heinz Pflaumer and Franz Wonisch to chase the other patents applicable to the PPX like the slide construction and lockwork. FWIW: They also worked on the PPS, and if you dig deep enough, you'll note that they came out of Umarex's design staff pool.

Tam said...

Well,

1) The PPS would be my choice of micro single-stack 9s at the moment, and

2) One of us is going to find out how well the PPX holds up to had use, and the other will read about it on the internet, nicht wahr? ;)

og said...

Actually, I like the patent better than the original idea. I would buy a spare barrel just to disassemble 9it, or see if I could.