Spandau Replica and Fokker DVII and assorted bits

[redbaron1917]

The foundry promised me a sample casting Wednesday or Thursday this week. I'll post a pic when I receive it and hopefully finish machine it a week later.

Also lining up another museum visit next week for more dimension checks on the feed block and a few other areas.

[redbaron1917]

Here are my first samples from the foundry. They look pretty decent. Can't wait to machine them. Have to wait until I get a few more dimensions verified. I am attempting to coordinate another visit with the museum next week.

Note: They are aluminum. Because bronze contains brass and brass contains lead, I may or may not get them cast in bronze later. California makes it difficult to make, paint or plate ANYTHING these days. If I am forced to stay with aluminum, anodizing or painting to a suitable matching hue will be done.

[redbaron1917]

Second trip to the museum was enlightening and disheartening Right side casting VERY close but not good enough for me. Only had 2 made, so not big loss. Feed pawl roller didn't scale properly from drawings I started with. Not off by much and I think only Dave Watts could tell . Strike 2.

I'll whittle out a new casting pattern and reprogram a couple parts.

I'll probably machine the 2 castings I have as setup pieces and post pics after that.

Spent 2 hours just on the feedblock alone measuring holes, radii, etc. It is a complex part and needs to be very correct for a replica to be proper looking.

Tony

[redbaron1917]

Well, here is one casting with 4 out of 5 machining steps. Didn't do the last one as no point. The pattern and casting are slightly off. It is such an exact science Need to redo. The last operation was to drill and tap the hole in the base for a detent spring and ball.

Anyway, concept seems to be good, just need a smidgen more material allowance on the pattern so the part will be big enough for cleanup to dimension.

Tony

[redbaron1917]

Just a little taste of what is coming down the road. Not shown are the cocking lever, cam, latch, synchronizer,Barrel jacket, Sight and muzzle. They are in separate assemblies.

The feedblock is a %@&#*# pain to draw and machine. Bear with me. I'll get there.

Working out a facimilie of the glide blocks to attach the cocking lever while I chip away at the feedblock.

Tony

[John McKenzie]

Hi Tony , ...Just one small point ...
Have another look at the C/sk riveted joint in the receiver housing ...Looking at the Front section (which contains the feed block ) , which incorporates the joggled flange joint , .... This jointing flange overlaps the rear side plates on their OUTSIDE , rather than inside as you've shown it .

Cheers John M

[redbaron1917]

Originally Posted by John McKenzie

Hi Tony , ...Just one small point ...
Have another look at the C/sk riveted joint in the receiver housing ...Looking at the Front section (which contains the feed block ) , which incorporates the joggled flange joint , .... This jointing flange overlaps the rear side plates on their OUTSIDE , rather than inside as you've shown it .

Cheers John M

Thanks John! I appreciate that. I didn't pay super close attention to that area on my last trip. I believe it is lapped inside, but just a bit thicker forward of the main side plate giving a slight outward joggle. Your thoughts? I am trying to figure out that bugger called a feedblock. Multiple parts and lots of machining/broaching steps in it

If only I could machine and fabricate as fast as I can draw I have studied Ray Hollings and the NASM drawings for several years off and on and nothing beats having occaisional hands on with the real thing!

I can only hope to approach your craftsmanship John

Latest assembly with more parts.

Cheers!

Tony

[John McKenzie]

Hi Tony ....A few dimensions that might get you pointed in the right general direction .

Generally speaking , the dimensions casings seem to have limits of at least some + or - ,005" or so , for not too critical stuff like the breach housings , but more critical areas will have much closer tolerances , and be classed into high and low bracket fits (this not concerning us right now) .
Inside dimensions probably being more critical than outside as this is where it all goes on .

I'm measuring in Imperial Inches as I just happen to have a vernier caliper of that type handy right now ...( but you can easily conv.to Metric.)

Starting at the front of the breach , just ahead of the feed block , the nominal thickness of the sides is about ,120" ..(But for about 1/2" Sq where the top cover pin passes through , and where this is ,205" thick .)

The Rear side plates Aft of the vertical riveted joint are nominally ,104" thick .

The INSIDE FACES of the ,120" thick walled Front ( machined from forging) section , and the Rear ,104" thick side plates ARE PRETTY EXACTLY FLUSH , such that you cant even "feel" the inside joint .
( Internal parts slide and work etc. in this INNER area and the inside of the breach Needs to be flat for smooth operation ....The "Joggle" joint is to the Outside ).

The Riveted Joint:- The Front section thickens up on the Outside face via a radius of about ,10" (estimate) , from its original ,120" by an additional ,070" which would give a thickness of ,190" over the last ,550" of its length .......However , this thickened " vertical strip" is recessed on the Inside face , by a depth of ,104" and length of ,475 " , in order to accept the ,104" thick Rear side plates , which recess into the front part by the amount of ,475" and the FRont and Rear sections are joined here by rivets , which are Csk inside and outside ....The vertical C/L of the rivets seems to be about ,26 forward of the rearmost vertical edge of the joggled front section ...(difficult to see in this light , with the flush riveting and aged surface etc.

Inside each of the rear side plates , just Aft of feed block , are the guide cams which control the movement of the "lock "...These may well be ,146" thick pieces , added on somehow to the inside faces ,and bring their over all thickness to ,25" thick at this point .. (rather than the side plates being machined from ,25" plate ).

At the rear , where the cocking levers reciprocate back and forward in its 1,03" high cut away recess / slot ; .....The area , on Each side plate Outside , top & bottom ,...is thickened up to give a longer lasting sliding surface .
This is done by riveting on (& ?sweating ? ) small ,08" thick plates , so increasing these areas to nominal ,184" thickness ...These additions each are of 1,94 long and ,43" high and ,08" thick .(except the LH lower * )
After afixing , these were machined to give a recess 1, 255/1,29" high ,with the newly formed lands thickness (was ,184) now being ,140" for the reciprocating sliding blocks to bear/slide on .
These ,08" additional bearing surface plates (fitted to upper & lower lands on each outer side plate slot ) , have side profile on the RH plate of rectangular form with 4 off ,20" radii on the 4 respective outer corners ...Similar on the LH side , but modified on the top rear corner to fit the top profile of the fusee cover ....and the lower one is longer , being extended rearwards * to include the rear lower "wedge" latch , that locks the back of the fussee cover in place ...( the upper wedge being integral to the rear " Butt plate" ) .

The bottom , inverted " channel" section cover plate is riveted on to become the integral base of the receiver ...Rivets C/sk on the outside only ....All fits between joints , and csk riveting are very well done and can only just be seen in good light ....but cannot be felt !

Hope this is of some help for you , I'm afraid I couldn't get a sketched sorted out due to a slight problem on the server right now .

Regards John .

PS Thanks also Tony , for you comments also on my FE2b thread , which I haven't yet had time to update .

Feed Block ....This was a forging or a casting and was machined by use of Milling , use of shaper * , and broaches , as far as I can tell .

* (Not same machine as that which you guys in USA call a woodworking spindle moulder .....but could roughly be described as like a pivoting vertical lathe tool on a "Ram" arm .)

[John McKenzie]

Hi Tony ...Ref Feed Block ....If you were to do a quick sketch of the areas where its a bit foggy for you , then I can do a bit of measuring and fill in the dimensions for you as best I can reach ...
Mark your required Dimensions as ..a , b , c ,...etc ..as I do not know how to do simple things like adding written dms to your pictures on the computer , but "I can" make a list of measured Dms which will key to your A ,b c , etc.
Bear in mind though , that for quite a lot of these internal feed block places , you'd/ I'd need special caliper/gauges to make these measurements , which I will not have to hand .

Don't forget that in the "Front" wall of the internal opening , against which the pointed noses of the bullets touch , there is an internal "leaf" type spring guide , which is fixed by laminating over the shaped Front guide-in lip , this being similarly shaped over , and riveted to it , by an appx 2 mm dia flush , csk on the inside , rivet , with the Rd head outside ...You can see this as what appears to be a "lamination " here .

Regards John M

[redbaron1917]

WOW!

Quite a bit of info John. Much appreciated. I have occaisional access to a couple of 08/15s.

I just didn't have enough time to finish checking dimensions and take notes. 1 or 2 more trips should finish it.

I am amazed at the overall fit and finish. As you pointed out, the seams and rivets are nearly invisible.

I was amazed to see 2 pieces riveted in the feedblock. This isn't apparent even with reasonably detailed photos. I had always wondered why I could make out a couple rivets on the feedblock.

I look forward to more posts on your FE. I am Will Rogers whenit comes to airplanes. I haven't met a one yet I didn't like! :-) The tailplane is magnificent and far more sofisticated than I would have known. The incidence bracket would make a great desk top piece by itself.


Best Regards John,

Tony Moore