View Poll Results: Which is most important to you when choosing a jetpump?
Having it look scale/highly detailed is most important 0 0%
Durability is most important 3 42.86%
Both: increase the price. Have it look scale, and be durable 1 14.29%
A balance between durability/scale looks. 1 14.29%
Other: Please leave a comment 2 28.57%
Voters: 7. You may not vote on this poll

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Jan 24, 2020, 02:18 AM
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Poll

Scale vs Durability vs Cost?


Which would you rather have?
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Jan 24, 2020, 03:26 AM
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I don't buy. I design and 3D print.
Jan 24, 2020, 09:59 AM
Jetdrives R Us
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I couldn't care less about scale appearance, it must work well. I decided to design a 3D printable jet drive because the cost was so high on larger pumps.
Jan 24, 2020, 06:54 PM
Registered User
Years ago people could make money selling this sort of stuff. With 3D printing the whole maker creativity thing has exploded and there are many people making great pump designs. To actually make money you need to cater for the lazy people who just want to splash out money on other people mowing their lawns, trimming their bushes and of course buying RTR RC jetboats.
I've always been most focussed on the concept and performance, I'm an ENTP or inventor personality. I'm weak on the S or Sensing component of Myers Briggs personality typing. So the people you market to are not DIYers but the superficially focussed Sensing personality types who self identify in around a 3:1 ratio to the Intuitives like me. Sensing types are all about appearances but from a manufacturing point of view, you really really do not want to sell flakey product, it comes back and gives you a bad rep, wastes distributor time, factory time and resources and eats up new product to replace poorly designed old. As people on this forum have mentioned before, scale jetunits don't work so well. This is mostly because of the high drag of high surface area to volume ratios on model jet units but it can be countered to an extent by increasing pump pressure i.e. more stator vanes, more impeller blades and multiple stages. Then they have smaller cavities which are more easily blocked but the filter grate becomes less of an issue as the intake speed doesn't increase, only the outlet speed as you are able to use a smaller nozzle.
At some stage I may design a multi stage unit. Others already have. Drag is proportional to the square of the velocity so it makes sense to confine the highest speeds to the outlet nozzle and slow the rest of the flow.
Jan 24, 2020, 08:34 PM
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grael you're right. Its the wrong audience here too. All us inventive folk hangout here and tinker. The money to be made would with the folks not hanging out here who want bullet proof and ready to run but are also prepared to pay for it.

What you said about the sensing types makes sense. I hadn't thought of it like that before. We prefer function over aesthetics. ie you'd sooner buy a tough-phone with a large battery than some shiny blingy one and same goes for jetboats and most likely a lot of your other equipment.

We're not far off in terms of scale? A 4.5 meter boat running off a 8 inch Hamilton jet pump for example would be the equivalent of a 650mm RC model with a 30mm pump. I did do a dual stage printed pump. Issues include easy to clog, one stone making a complete mess of the printed impellers and stators. And that's not to mention the noticeable efficiency loss. I think a lot of that can be overcome by using a stainless steel wear ring, metal printed impellers ($20 each) and perhaps printed stators but I dunno it just gets a bit out there.. where do you stop.

The only way I see to go commercial is to make a very nice shiny scale boat working out is if I were to go the metal 3D print/machine all the parts. R&D costs would make it unviable not to mention limited audience.

Or, perhaps cater to the makers out there and make cool designs! (done one of those, it worked out to about $2/hr of time spent on it after you take out parts/materials etc but at least a hobby is cost neutral this way).

Ah well...
Jan 26, 2020, 02:44 AM
Registered User
Quote:
Originally Posted by TTN
Or, perhaps cater to the makers out there and make cool designs! (done one of those, it worked out to about $2/hr of time spent on it after you take out parts/materials etc but at least a hobby is cost neutral this way).
Ah well...
If you want to compare notes sometimes, rcgroups says you're 23km from me, I'm in Porirua, Ranui heights.
I've contemplated getting one of those Chinese induction furnaces, you can get the budget ones for $400 and upwards and can then metal cast into lost-PLA ceramic void moulds. There's a lot of pleasure in getting a good design out there but it's a lot of hard work for a different personality type than me to actually turn it into a business, that's not where my talents lie.
I think you're on myminifactory or youmagine?
I get quite a few emails from pinshape when people upload my stuff but my stuff has been free so far. Still, I only have a few designs on there, on thingiverse I'm up to 54 headings. I've read you need around 100 good products for a designer's sales to really take off. I'd have to say, pinshape seems to be getting a fair bit of traffic based on my notifications. I get slightly more for thingiverse but have so many more designs loaded there.
Jan 26, 2020, 04:13 AM
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I'm based in christchurch but that's not to say a visit couldn't be arranged. I'll be passing through wellington sometime near the end of February.

I did actually try to cast some aluminium into a print. Mistakes made were not burning out the mold properly (rather, it was melted out at 250c ), the mold wasn't preheated enough and the parts were only 2mm thick in places so that didn't go so well in a cold mold. I think using shapeways for the metal bits would be a good way to go as there's a fair bit of work in casting.

Yea, I'm on youmagine, thingiverse, CGtrader (I like this one best). Thingiverse is cool but their site is bit clunky and I think it'll go offline one of these days. The issue with myminifactory is their website just isn't as good. Can't upload zip files (terrible when a project has many many files and I'm putting up different revisions - gets messy real quick). Whereas on CGtrader I can manage it a lot better.

100 is a lot of designs! Haven't got that many yet.. far from it.
To me it seems the trick is to leverage the new digital manufacturing methods, shapeways, 3d printing. I love 3D printing its awesome. Honestly I do this mostly because I just love to tinker.
Jan 27, 2020, 04:03 PM
Registered User
Quote:
Originally Posted by TTN
I'm based in christchurch but that's not to say a visit couldn't be arranged. I'll be passing through wellington sometime near the end of February.

I did actually try to cast some aluminium into a print. Mistakes made were not burning out the mold properly (rather, it was melted out at 250c ), the mold wasn't preheated enough and the parts were only 2mm thick in places so that didn't go so well in a cold mold. I think using shapeways for the metal bits would be a good way to go as there's a fair bit of work in casting.

Yea, I'm on youmagine, thingiverse, CGtrader (I like this one best). Thingiverse is cool but their site is bit clunky and I think it'll go offline one of these days. The issue with myminifactory is their website just isn't as good. Can't upload zip files (terrible when a project has many many files and I'm putting up different revisions - gets messy real quick). Whereas on CGtrader I can manage it a lot better.

100 is a lot of designs! Haven't got that many yet.. far from it.
To me it seems the trick is to leverage the new digital manufacturing methods, shapeways, 3d printing. I love 3D printing its awesome. Honestly I do this mostly because I just love to tinker.
I made a furnace years ago, it wasn't that good but let me experiment with metal casting a bit. Made a weedeater powered jet unit with it that went OK. Interesting to hear of your PLA experiment, I presume you used plain clear PLA?
Haven't tried cgtrader , I'll check it out though, thanks. And thingiverse… I think they aren't properly financed after MakerBot's failure, any new things I put on there don't get renders anymore, I think for the last couple of months. I've used shapeways a bit, I'm halfway to the minimum for a shop payout but not expecting it any time soon.
Jan 28, 2020, 01:42 AM
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Quote:
Originally Posted by grael
I presume you used plain clear PLA?.
Just used what I had on hand which.. was not clear.

RE: thingiverse, their TOS states what you upload becomes theirs in essence so I avoid it.

What's your thingiverse link? I'd be keen to have a look at your other cool stuff.
Jan 28, 2020, 03:36 AM
Registered User
Quote:
Originally Posted by TTN
Just used what I had on hand which.. was not clear.

RE: thingiverse, their TOS states what you upload becomes theirs in essence so I avoid it.

What's your thingiverse link? I'd be keen to have a look at your other cool stuff.
So PLA+ has another type of plastic blended which probably doesn't burn away cleanly. The pure PLA variants with colour have coloured "masterbatch" pellets added to the normal pellets before they are all ground up with the normal PLA pellets. Likely the masterbatch pellets are PLA too but I wouldn't be 100%, just not all plastics will melt homogeneously into PLA. In any case, there will be least residue with pure PLA(clear or natural).

I'm on thingiverse here: https://www.thingiverse.com/fluidity/designs and shapeways here: https://www.shapeways.com/shops/grahamdaniel

Not much jetboat stuff there but I started a new thread on here after the 4BDN hull thread, I'm a novice at CNC routing and I'm contemplating the best way to route out my latest design here: https://www.rcgroups.com/forums/show...kinnedMono2020

I was originally planning to do it in one operation on HD foam as I have a 120mm z axis range but then I discovered that I was going to be more constrained by the tool lengths! So I'm now thinking to switch to 18mm ply or custom board and slice my model horizontally into 18mm layers to do it in sections so I can use shorter milling bits. After I do a finishing operation on each section, paint it with gel coat to seal the voids, wait for it to cure and then re-run the finishing operation.
Certainly nothing like the jet sprint hulls but the different design is very intentional.
Last edited by grael; Jan 28, 2020 at 04:39 AM.
Feb 15, 2020, 09:52 AM
TRUMP 2020

pump


No one is making a jet drive, none of them have use a proper impeller design. (see link below)

All they are building are kort nozzles.

https://www.ebay.com/itm/293447826158
Feb 15, 2020, 02:56 PM
Just Plane Nutts
AirDOGGe's Avatar
Left one choice out...

Scale Accuracy:
Item Durability:
Pump Performance: (Check this box)

Function before form is my rule.
Feb 16, 2020, 12:17 AM
Registered User
Quote:
Originally Posted by Fourtech
No one is making a jet drive, none of them have use a proper impeller design. (see link below)

All they are building are kort nozzles.

https://www.ebay.com/itm/293447826158
Looks like part of a mixed flow pump? (combination between centrifugal and axial flows). I think the Colorado did that.
Feb 16, 2020, 02:20 AM
TTN
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Quote:
Originally Posted by grael
Looks like part of a mixed flow pump? (combination between centrifugal and axial flows). I think the Colorado did that.
This is a impeller from (or very similar to) a berkley jet pump.
Feb 17, 2020, 12:01 AM
Registered User
Quote:
Originally Posted by TTN
This is a impeller from (or very similar to) a berkley jet pump.
Thanks
I wonder how they keep grit from the outside part to it's surround?


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