OSTexo - I'm working with BurrMan on it - we're probably in the last revision, but yours is a nice start. I'm running a test print of Rev.2 from BurrMan now.

Sure nice to find experts on MOI around - I should have called out for assistance months ago.

Hello,

Understood, I'm making sure I understand the model so I can improve my skills, not looking to get in the middle of anything, e.g. trying different methods to get the end cap matching with the body of the part above G1.

I just ran it thru netfabb and Kisslicer for a test - it slices clean with no artifacts. I'm a bit chagrined that others have figured out how to do this, when I failed utterly...

Hi Rick,
Just so you know, the great point about doing it in the forum is others can help out.

I'm not so sure about what I'm making either. Would love to have others participate.

Like the "50 mm".... I've been having that be the "tip" ( the point at the top is 50 mm up the curve..

Here's another revision. This is using some sweeps and a blend to cap the end.

I have to run out a for a bit. We just need to get nailed down what you need. (The sizing off in the last part was just me and my generator curves. This can be set proper once we figure out what the part should look like, and where the dims you mention should be.

Also, yes. You should come in the forum long before you get frustrated. You'll find many users that can help.

If you can crop the to half sphere a little bit, you can end with a nice g2 continuity too ... but I'm not sure I completely get the problem either, language barrier :)

That's a really nice transition - enhances the shape quite a bit.

Hello,

PaQs model zebra lines. This part fits to the end of a fencing sword handle?

Here's a video of what I think PaQ is describing.



I'm still a little unclear on what some of the measurements are with regard to the geometry that was in the original files. Like the 27.5 part.

Anyway, I also showed a couple cuts to represent the "15 mm" cut in the bottom? Wasn't sure how that was supposed to go. If either of those are correct, let us know.

Once the shape is nailed down to what you want, we can discuss various ways for you to get it done.

[EDIT] in the video I just used a tangent blend. The file attached is what PaQ referred to, where I recut the sphere to be just a half sphere, then I could use a G2 blend so it was smooth.[EDIT]

Hello,

BurrMans zebra line part.

Yes - this is a new take on a Pommel - the part that screws onto the end of the tang of an epee, holds the French-type handle on, and serves as a counterweight for the blade. All previous pommels are basically tapered cylinders run on a lathe.
With a French grip, one is allowed to hold it anywhere along its length, but the tradeoff is less wrist-driven power than a "pistol" of orthopedic-type grip, vs. a couple of inches of extra reach and fencing with "absence of blade", i.e when the opponent tries to take control, the French-grip fencer simply evades blade contact, because manipulation with the fingers is faster than with the wrist. I've attached an image of the prototype I fence with.
Once the brass insert is melted into place, the fencer can then insert lead of tungsten shot, to get the exact balance desired for the epee - the other unique aspect - adjustable weight.

I think draft5-g2 may be just a bit too bulgy for the purpose, but I'll print it tonight and see how it feels. I think that the flare at the waistline is not going to work quite as well as the straight sides just merging smoothly into the dome. Needless to say this is very subjective, but I'm guessing the little finger won't fit quite as well on the bulge in 5-g2.

As to the 27.5mm - that is the diameter of the waistline where the cone meets the dome, and thus the diameter of the dome.
20mm is the diameter of the base.
The 15mm is the height of the solid portion at the bottom, which the (needs to be straight but dimensioned as at McMaster-Carr link) hole pierces.
Above the 15mm, the rest should be hollow, with 2.5mm wall thickness.

Getting real close. I'll do some test prints, and be back in the morning (we're shut down here in Portland, with an inch of freezing rain on top of 10" of dry snow).

Hey Rick,
So don't do a bunch of tests yet. Things like the "bulgy" aspect can easily be changed.

I think the main part first is to see if the "hollows and solids" are as they should be along with the basic dims. (For instance, I made the walls 3mm thick. You just said 2.5mm, so that would have to change still). Look at how the 15 mm solid is made and mention if that's correct. After those are all correct, we can look at a file where you get the shape you want. Even set you up to do some variations yourself. (Like note Paq's shape has not the same dramatic bulge) You'll see me set the sphere at an exact 45 angle. Is this non-negotiable? A slight rotation back on that would remove a good portion of that bulge, fairly easy.

Also, with regard to the 27.5 radius area (Where the "sphere meets the body"..... There will be a difference in that area being some sort of sweep or flow through those dimensions, and getting a curve of something "other than a perfect 27.5 arc", but that doesn't mean it's not conforming to those dims. The construction will be much more limited if you "must have an exact arc there".... Just a note.

Talk later.

This is my version :) Free of charge, of course. ;)

Just so you have something to reference, here is the object using the blend method with tangency. You can also note in this one I rotated the upper sphere a bit off of 45 degree's. This makes less "bulge", but maintains the basic gist of the part.

Anyway, talk later.


[EDIT] Foiled by Max!!!! [EDIT]

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