I'm currently test-printing Burr's v6, because a lot of the 3D printing design process is a matter of how the slicer and printer interpret the design - they are very interactive with the CAD. I've printed hundreds of these things while honing the process.

So far, so good - it's so close that I'm practically hyperventilating about releasing and shipping this product, the Melting Pommel, this week.

The exterior shape is perfect enough for this planet, the walls are 2.5mm, and it's printing really well on my TrinityLabs Aluminatus. http://trinitylabs.com/products/aluminatus-evo1 (Mine was the half-priced Beta version - considerable assembly and effort involved at the time)

I'm very excited to get this one done, as I'm supplying a couple of Rio 2014 Olympics candidates with pommels (this and the Palmel version linked above), and I believe that this one will become very popular, while stretching a couple of hidebound fencing rules to the limit and offering considerable advantage to fencers who use it.

BTW, this is pretty much a charitable activity on my part, as the market of Epeeists who fence Extended French style is very small, and very conservative. I'm producing these because I believe they can cause a significant change of balance in the sport, from advantage to those power-fencers who use a pistol grip toward those who use a French grip. So far I'm into it to the tune of about $5K, and chances of ever making that back (much less my time) are infinitesimal.

More detail on this version in an hour or two, but it's soooooo close.

Burrman - as far as I was concerned, your draft v6 was basically perfect shape. It appeared to have 2.5mm wall thickness, if I'm not mistaken? This latest seems to have 3mm walls? 50mm total height to the top is correct. There is a rule re. aggregate length of grip plus pommel that I don't want to violate. (There is no rule on the shape of a pommel.)

Aside from that, it's not clear to me what the differences are from draft_v6 to working_file_draft.

The only things I'd like to change from draft_v6 would be:

- The top surface of the 15mm solid at the base base would be better if horizontal instead of tilted, for a little more strength. If one of these things ever broke in a tournament and spilled hard-to-vacuum metal shot on the conductive strip, it would instantly be the end of this whole venture.

- The stepped/tapered hole needs to be stepped and tapered per McMaster spec. for best strength. I heat the brass inserts up on a special soldering-iron tip and melt them permanently in place, and the join needs to be as strong as possible. http://www.mcmaster.com/#94180a373/=qmf0sf

- 2.5mm wall thickness seems to be optimum for printing.

Sooooooo close to production...

Also, PaQ and Max - both of yours are really close to the target, and it's interesting to me that there appear to be many routes to making this model, all of which I managed to overlook.

I printed a set of PaQ's version (I print them in threes, to allow time for cooling) and mounted one on a blade, but the bulge toward the dome just didn't feel quite right, or at least not what I'm accustomed to.

It's not obvious, but to get this correctly oriented to the blade and handle, one needs a set of shim washers from .5mm down to .05mm (.002"), and the stainless washers are Expensive. The .05mm shims I supply cost me about US$2.00 each, and the set of five costs me around $5.00 total.

So, I'm considering Open-Sourcing the design, which might accelerate adoption by fencers, as having an online retailer or two just isn't enough marketing to get it out there very soon, and there aren't any real Fencing storefronts. Anyone who can price it lower than I can would only get the design in front of more people sooner, and I'd even sell the insets and washers in small quantities. My goal is to tilt the advantage in the sport from pistol grips back toward the original French grips.

I'll offer these direct online at $15, and I'm working with a French grip manufacturer, as I have little interest in shipping small parcels: http://www.harutfencinggrip.com/

If I can print a dozen or two final copies in the next few days, I plan to attend a Junior Olympics event here in Portland next weekend, where I'll chat with several vendors who might carry the two pommel products.

Hi Rick,
"""""""""""" It appeared to have 2.5mm wall thickness, if I'm not mistaken?"""""""""

It should have.

""""""""""Aside from that, it's not clear to me what the differences are from draft_v6 to working_file_draft."""""""""""

The original setup was kindof mangled and most likely what was causing your poor stl translations and such. After we get your part done here, I'll make a final video that addresses your initial issues with it, and also try to show you some "Move" and "align" techniques to help out. I know your frustration was looking for methods you were familiar with from other apps. MoI will do those types of moves too, but you may get some good input on that. Lets just do that after so we don't confuse whats going on.

"""""""""The only things I'd like to change from draft_v6 would be:""""""

Here is draft v7. It addresses what you mentioned. The file itself has the "insert" left undone... I've included the Mcmaster part sitting in place (green style).

I've also made a video, with audio that describes how the part is made. I start with draft v6 and re-create the part.

The bottom insert needs to be made. This would be a shape extruded up from the zero point to 15mm, then Boolean diffed out of the part (don't forget to delete the 2 solids in the cavity after this)



I left it for you to tackle? If you are uncomfortable with this, I can do it for you. I just wasn't sure after seeing the part, because we were doing a 9mm radius throughhole, and the part itself seems to be bigger than that? Let me know what you want.

I forgot to attach the file. This file also includes a taper made to the specs at McMaster. But I'm not sure how it's applied? It doesn't fit the McMaster part, or punch all the way into the cavity area. You can either do this, or give some direction on what it needs.

[EDIT] Also, I think I have the insert situated upside down. [EDIT]

"The bottom insert needs to be made. This would be a shape extruded up from the zero point to 15mm, then Boolean diffed out of the part (don't forget to delete the 2 solids in the cavity after this)"

Huh? You are talking about the 15mm tall "plug" that fills the bottom end, and contains the tapered hole? I think I get the Boolean, but what two solids in the cavity?

Nice job on the insert, but that's upside-down - the narrow end goes into the stepped and tapered hole that they call out, at 250C, and the ridges on the hot brass insert push melted plastic forward into the serrations and ridges as it slides in, for a really solid permanent embed. The hole needs to be wide end at the bottom, and shaped like the attachment. The 9mm figure was just a guess before I spotted the hole shape at McMaster.

Tapered Hole Diameter, mm
(A) 8.2
(B) 9.22
I'd put the narrow straight part of the stepped hole at about 2/3 of the way in, guessing from the sketch. The straight part of the hole needs to go all the way through the plug to the interior, of course.

Warm thanks once again, for your incredible work and sharing how you did it.

"""""""""Huh? You are talking about the 15mm tall "plug" that fills the bottom end, and contains the tapered hole? I think I get the Boolean, but what two solids in the cavity?"""""""

When you cut the "insert hole", the cavities will have little solids inside. It could be a bug with how the Boolean was performed, I'm not sure. Lets just finish it here so we don't get confused.

So, the tapered dims, fit to the insert look like this:





If these are set at the baseline, this leaves 2.3 mm before the cavity is reached.

Would you like to inset the tapered hole some? And, if we inset it, would you like the taper to continue out, so that the 9.22 starts at the inset value and the actual base opening is now larger? Or would you just like the opening to be 9.22, straight to the inset, then perform the taper?

Let me know and I'll finish off the plug hole

No, it can't be inset at all, because the fencer will screw the pommel/insert down onto the grip (and the shim washers) as hard as their hand can, so the insert has to be flush to protect the plastic from pressure that could break the insert loose. The fencers want the pommel/grip/bell-guard/blade clamped down as hard as they possibly can, so nothing comes loose under the impacts of vigorous fencing. (I also recommend a drop of Loc-Tite. On my first metal pommel design, fencers griped because I didn't include flats for a 3/4" wrench to tighten it.)

I set it flush when melting it in, by pressing the base of the pommel with still-hot insert down flat on a metal table. It's in there forever after the plastic cools and shrinks.

The straight portion at the top of the hole should just be extended the 2.3mm at same diameter, upward into the cavity, to allow the threaded tang to protrude into the cavity unsupported. Many of the threaded tangs will extend further in than 13mm, and need to do it without hitting anything and breaking plastic. The uppermost couple of mm of the 15mm tall "plug" is there to spread the stresses from the end of the brass insert into the cavity walls.

So far none of my prototypes have broken in use, even when using brittle PLA plastic, but I take my design guidelines from the Navy: Design it strong enough. Then make it three times stronger than that...

Ok Rick. this file should be it....

Just note that the base rim of the insert is 9.53 in diameter (the green), while the tapered plug cut was made at 9.22. But I guess you understand how this "melts" into place...

Let us know if you need anything more about this...

That is Perfect, and I cannot express my gratitude for your work!

:)

I can be proud I helped you.

I'll make a couple vids later regarding the start/beginning point of the process.

Well done Burr! great to see a real product life cycle unfolding on the forum.

Cheers

Thanks Danny! It's going to be great to see some guy "Perry" some poor chap with one of these!

I was stoked we got what he needed.

I think Rick was stuck with working in MoI because he is experienced with another app/workflow.

I'm going to make a couple other vids on it for him. Feel free to input on other methods or mistakes you see me make. This is NOT a paid venture (Ricks to kind to ask for "free" help).

Talk later.

Great job Burr!

- Michael

What a Great Forum. MOI's creator must be an incredibly nice guy to have spawned such a good group.

I'm now fine-tuning the printing, and will get this on the market this week!

Hope you'll post some photos of the printed results!

- Michael

..hey Rick... you have found just the right man to ask an help... :)
you're lucky !

Sure will - I'm in production now!

Just a quick update:

I attended a Junior Olympics Qualifier Fencing tournament in Portland over the weekend, hooked up with a well-known vendor, and he ordered 100 of the Melting pommels on the spot. After I sold him the 30 or so that I had in stock, I ran completely out of parts and plastic, so I've been frantically working on getting shim washers, brass inserts, and plastic since then.

I haven't shipped any yet, but will within 10 days or so, and will send Burr one as a memento and Thanks for his invaluable help.

That's cool Rick!

"""""""""I haven't shipped any yet, but will within 10 days or so, and will send Burr one """"""""""""

Be sure not to worry about it while your swamped.. Get all the orders filled first! It's not necessary, but THANKS!

Good luck.