Spec Boot For Mk-15

[lowviz]

So the airless mixing tips (that allow one to ignore vacuum degassing) turned out to be stepped, not tapered. See pic. :sigh: Makes sense, though. Their stepped mixing tip will connect to nearly any standard tubing much better than a taper.

Now I'm sharpening a raft of itsy bitsy end mills that will have to be run in (accurately) one at a time to duplicate the steps.

Durometer. I had the presence of mind to ask Smooth-On to send me samples from 10 to 60. See other pic. Most informative, nothing like holding it in your hands. More kudos to Smooth-On.

We press on...

Hey Tigger! Thanks!

I didn't have the 60 psi spec. Thanks again. Yeah, I have a big vacuum pump, but trying very hard to avoid needing it. Trying to make this something that most shops/craftspeople can do without a lot of heartburn.

 

[lowviz]

OK, so now you are addicted.

Yeah, kinda drags you into it. You do know that your silicone will withstand pot metal (zinc diecast) temperatures?

...//... I talked with Smooth-on and they say their platinum cure silicone (Smooth-Sil series) is compatible with silicone oil. I have some cured samples coming for my other project (TiggzCraftwork). ...

Wow, that is big! I didn't get that when I called.

I have some "Dow Corning 200 Fluid" that I'll send you for a soak test if you get some Smooth-Sil. Would be interesting.

 

[lowviz]

I now have enough done on the mold container to lay out my plans. I've pocketed clamping flats for my step blocks and set-up clamps. Couldn't just run the mill bit straight across because I need the meat for the mixing nozzle. Plans are for two top plates. One out of Plexiglass (Perspex) and one out of aluminum plate. Big holes in the Plexi for pouring the mold resin, tiny holes in the aluminum plate for releasing air when the part is injected.

I plan to temporarily glue the SPEC boot to the plexiglass cover to make the mold. Still following Tigger's procedure, all I'm doing is making a containment part to prevent the mold from ballooning out under pressure from the caulk gun.

More later, progressing nicely.

 

[lowviz]

......keep the cards and letters coming.

OK.

Well, this thread has evolved into a DIY thing. I haven't heard any complaints from the reg guys/gals so the thread might just as well remain here as it is all about SPEC boots. (Mods, feel free to move it without asking if you wish.)

Got past the hard part. Machining a 2 1/2 inch through-hole is a challenge or requires expensive tooling. Trick from an old dog machinist: Use a high-quality speedbore bit (that is only intended for wood). Cut the shank as short as possible and run it in slowly. Use liquid hand soap as a lubricant. Worked like a charm, see pic. I used an Irwin 1 3/8 bit, forget cheap imports! Now I can run a fly-cutter in as the hole is large enough so that the quill will follow it in.

All downhill from here...

 

[lowviz]

Forgot to be explicit with the UN-RECOMMENDED operation of the Speedbor bit. Here it is:
Irwin 88822 Speedbor 1-3/8" x 6" Standard Length Spade Bit - - Amazon.com


Oh yeah, don’t forget to drill a pilot hole or you will break the tip off in the Al blank and you’ll have to chase the hardened steel chip out with a carbide cutter. The through hole that I drilled was about 2/3 the max width of the Speedbor tip. Anything close to that will work fine. Pick a drill that best matches your closest collet to the desired size.


All ready to run the fly cutter using a non-directional bit. That is a very unbalanced tool. One cutting edge way off center. Hammering. Oh jeez, it finally caught up with me.

Gibs and ways tonight... :sigh:

 

[lowviz]

Gibs and ways adjusted, head re-trammed. All is well. See pic.

The devil is in the details. A Mark-15 boot (couv's) is about 4 cc, a Mark-10 boot (uncfnp's) is about 2 cc's of material. The 50 cc's of fancy fluorosilicone has a pot life of 3 hours (guaranteed) and 7 hours as the spec for this lot. I'm going with 7 hours. The cure time is 30 minutes at 150 degrees C. It is obvious that I will run out of time and waste material if done one at a time. I need one mold container and multiple molds.

Planning to use a slitter saw to part the aluminum mold container so that I can inject, rapidly break open, remove mold, load another mold, repeat, then and bake the filled molds in batches. No other way to beat the clock...

 

[raftingtigger]

lowviz, can you give me the dimensions of the MK10 SPEC boot please? How thick is the rim and how deep is the inner chamber/groove. I finally have my MK5 apart and am going to machine some blanks/molds.

I'm guessing the rim is 4 mm thick with a 2.5 to 3 mm packing material chamber.

 

[lowviz]

Best if I send it to you. You will see that one side of the MK-10 SPEC boot is a bit compressed due to heat/age/oxidation. Machining a form would be the very best way to proceed. I'll need it back, though. It isn't mine.

The liquid injection mold is progressing well, almost done.

 

[raftingtigger]

Sure. Send it to me. Address per PM.

Another potential project. If I can get them to work is anyone interested in color coded 109 (2nds) faceplates? I'm thinking Simpact 85 might work.

 

[lowviz]

MK-10 boot is on the way, check your PM's for the tracking number. I'm planning to make a mold from the original MK-10 boot when I get this liquid injection molding thing squared away. Maybe a pic for discussion tonight.