3D Printing

[Vodkaman]

Also known as Rapid Prototype (RP).

Obviously a lengthy read, only really of interest to those thinking about using RP or wanting an alternative to sleeping pills.

I had no personal experience in this field when I decided to use RP for a project, other than what I had read from a few simple Google searches. I found a couple of local service providers, not wanting to go international postal, I decided that these would have to do.

Their print area was not spectacular, so I chose the largest of the two which was 14cm x 14cm x 20cm.

I had questions that were bothering me; Firstly I had seen 3D prints on the web of assembled parts printed out as an assembly, also the traditional ball in a ball thing. This made no sense to me, as the parts would have to start printing in mid air. Also, if I gave a positive fish model, how could it possibly print, as the contact with the ground plate is minimal.

I submitted a positive fish model as a test, to see what came back. Unfortunately they took so long that I jumped the gun and submitted my mold model, which was a mistake on my part. Still, plenty was learned from the two models.

The bluegill came back looking a right mess. The model that I provided was split into two halves and glued together after printing. The join line was along the lateral line. There was a quite heavy seam and a mess of glue. Had I known that this was the method of printing, then I would

have printed two halves and carefully glued them together with more precision myself and made a far better job. The only scruffy parts of the print were the rear of the dorsal fin, which is an overhang and the rear of the ventral fin for the same reason. To understand these issues, deeper research was required.

I was right, the process cannot print on fresh air, so what the print software does, is print from the base, a rough support structure, to support the model for printing. This structure is then manually trimmed away and you are at the mercy of the guy doing the trimming. It was not too bad, but I could have done a better job myself.

When the mold parts came back, it was plainly obvious that holes in anything but the vertical were not possible with any accuracy. The 20mm diameter piston hole came back as an elipse with a 1mm error. I had to significantly trim the piston down to get a free fit, but the 1mm gap on the long axis of the elipse meant that it leaked like a sieve and there was not enough pressure to fill the mold.

I designed the mold with spherical locators and depressions, I also included undersize holes for bolting. This was a good decision as the locators did not fit, being too tight. I drilled out the holes and then removed the locators completely.

The next problem was that the mating faces were far from flat, with a significant warp, despite the fact that I included a lattice work behind the face, to add stiffness and reduce the likelyhood of warping. The plastic was however soft enough to pull together, but a close seal around the cavities was not possible with the edge bolting and leaky gaps occurred and combined with the inneficient piston, prevented the mold from filling.

The surface finish was far from smooth, but this was no surprise given the layering method for depositing the plastic. This I was prepared for and willing to accept.

I have just coated all the mating surfaces of one side with a contact adhehive, in an attempt to lay down a rubber gasket. I am hoping that this might allow me to get a few complete pours for water testing.

When printing the mold halves, the guy again split the model to enable printing. Unfortunately right through the mold cavity, making the mold

useless for anything other than a rough prototype.

Other problems occurred, but these were with my model, with the fins being too thin.

Rapid prototype is not cheap, the bluegill positive and two mold halves cost me just short of $100. This is not too bad considering that carving a master to this standard would take me days and ultimately not achievable for someone with my carving skills. Printing a positive master is a good plan, as the rough surface finish can be fixed with a thin coat of epoxy and a turning wheel.

Conclusions - first impressions would be that this was a total waste of time and effort. But time is never wasted when exploring new techniques.

In fact, once you understand the limitations of the RP process, it is possible to design something that will work.

My plan now is to fix the computer model and make an RP mold master for pouring plaster mold halves. The mold halves will be symmetrical, so only one master needs to be printed. Once the plaster molds are poured, dried and drilled, they will be skimmed flat on a large sheet of emery paper. This technique will allow me to produce as many molds as I require for production, plus replacements in the future.

The built in piston idea cannot work with RP, so I am going back to vacu-venting as I believe that I can make this work. I also think the vacuum method will allow me to achieve the fine detail and a four cavity mold.

So, more work time and money to be put at risk, but who's counting. This is what I do - experiment.

The image shows the mold halves and the piston. The right hand piston was printed in the vertical and shows how the software built up structure to support the model. The piston was eventually split and printed horizontal.

Also included a pic of the bluegill positive, showing the split and messy glue.

Dave

Edited August 14, 2015 by Vodkaman

[mohawkman]

Good read, thanks Dave. I've been looking into 3D printing but haven't pulled the trigger yet.

[Vodkaman]

It is best to get your stuff printed out by someone else first, to evaluate what you will be getting. Look for someone doing it as a hobby or side-line as they will have a machine similar to what you are looking for.

If you are not intending to buy, then go to a company with a $500,000 machine and get the best possible quality. These guys print multiple projects at a time.

DAve

[Vodkaman]

Bob - I was hoping that it would help us in our collaboration. To test swim the customer's baits prior to machining.

Of course, the customer would have to add $150 to the design and wait another week. But for the more outrageous baits and those trying out new ideas, this could be a worthwhile exercise.

For this extra cost, the customer would receive a video of the swimming action, from above and under water.

Dave

[mohawkman]

I've been looking at buying a Makerbot digitizer and 3D printer. It's too much to spend on this hobby, according to my wife. I may buy it without her knowing. It's easier to ask for forgiveness than it is to ask for permission.

[Vodkaman]

You are going to be trippin' over a lot of new shoes!

Be sure that you can make the machine do what you want it to do - BEFORE you sign.

Dave

[mohawkman]

I suppose I should do some reading and research before I pull the trigger. I'm a "shoot first, ask questions later" kind of guy. Gets me in to trouble sometimes.

[JRammit]

I wouldnt think a 3D printer would be necessary for the hobbyist

Unless you plan on the machine paying for itself in something more than fish fillets, there are other options

I have a cheap 3D printer, its says dremel on the side of it... It has "printed" the master to every soft bait ive made

The baits may not be "shelf quality"... But my "customers" breathe through gills and have brains the size of marbles

[jonister]

I found a 3d printer for like a grand or so at homedepot, it interested me but right now im not in the place to drop thousands on something i know hardly nothing about. Mohawkman, id hope you ask first! We bought a boat without asking once..... lets just say im still hearing about it today. 

[Vodkaman]

I am a professional CAD designer, so I can make CAD do ALMOST anything I want it to. BUT, I still have to carve my lure masters by hand and to me, this is a crime. I want one. When I am done experimenting to find the limitations and how I can make it work for me, and when I can spend the money without putting myself at risk, I will take on the risk and get one.

The risk is will the level of machine that you are prepared to pay for, do the job well enough for your requirements. How stable will the machine be and will it need constant servicing.

Anyone out there thinking of investing in such a tool:

Firstly, without the CAD expertise you may be wasting your money. First you must get a decent CAD system that is capable of the models that you wish to produce. You must spend a lot of time (months) learning how to make the CAD system do exactly what you want it to do. In the early stages you will be tempted to think,'well, that is not exactly what I wanted, but it looks good'.

Do your research. Read independent user reviews, NOT company BS. Sign up to one or two RP forums and ask questions. Ask nice and you may be able to get a model printed off on the machine model that you are thinking of buying.

Evaluate the risks and accept them. Don't cry if it all goes wrong. The money has to be written off.

You are most unlikely to produce enough work to justify this machine, but that does not mean that you shouldn't have one. You may be able to offset some of the costs by doing work for others.

Dave

[Team Frankenmerc]

I was able to take my design to the local college and talk their CAD department into printing my lure I wanted a master of. They ended up printing me 6 copies because I was able to just mirror the image to use the space available on the table. Might be something you all might want to think about before buying one. See what they use and the quality. Also while I was there they gave me many pieces from other abandoned projects that could be used as blanks for bait designs. All of my baits are one of a kinds drawn, molded, and poured by me. I enjoy catching fish with something I truly created.

[Vodkaman]

I would like to see an image of your master. If you don't want to show then I totally understand and respect.

DAve

[Team Frankenmerc]

Here is one of them without giving to much detail away. I love the design and the detail you can put into it using the 3-D printer. I only have used plaster molds so far poured by hand. New ideas coming soon for methods and technology. Mini mills and 3-D printing combined. Wow.

Edited August 24, 2015 by Team Frankenmerc

[Vodkaman]

Thanks TF.

RP is very good for making positive masters. The surface finish is the main problem, but this is easily fixed with a coat of epoxy, rotated to achieve an even surface.

Dave

[Travis]

You would be surprised at how easily it is to find guys to do this sort of stuff.  Especially when around colleges and universities.   Besides classes (engineering department) they have 3D printing clubs (I was told over 125 showed up for the club call when discussing this with a new hire at work).       They typically take on projects to help fund the fun.  I found the 3D scanning rather interesting.  They were scanning their heads and then printing small busts of themselves.  Not for sure what costs would be but likely cheap depending on how you break it down and what one is trying to accomplish.

 

I have a coworker that said he could do some stuff for me if I wanted but never took him up on the offer. As Vodka mentioned not something you just walk up to and start churning out.   It did take him some time before he started printing some nice pieces. It was interesting to watch his progression as it started out rough (understatement).  Programming issues and just learning the ins and outs of what he had build.  He picked it up rather quickly, probably a good year, and started turning out some really clean pieces that we use in the lab after he figured out some of the odds and ends.   I think everyone had little nick knacks for some time as he was working out the bugs, nozzle size, temperatures, media, etc.....

 

 

The bluegill looks pretty good.  Looks like a fun project.

Edited August 25, 2015 by Travis

[Vodkaman]

Thanks Travis, yes it is an interesting project, the first time that I have gone to such detail.

Cost wise, the Rupiah number converts to around $70 but this is for a 2 part, 2 cavity mold, not just a positive model. I consider the cost very reasonable. It should be about the same price over there, as I am suspecting that I am being ripped off over here.

I think of it in terms of time and money; how many hours would it take to carve the master and make the mold, at say $25 per hour. In those terms, the RP model is very cheap.

Dave

[ravenlures]

I was watching a TV show called THE PROFIT and the one owner was printing on Baseball bats and other items using a printer, has anyone ever seen one of these printers or used one. I would like to look into it for fishing lures.

 

Ravenlures

Wayne

[Mitch Fields]

Unless you use PolyCarbonite or Ultem you won't get a mold that will hold up to the heat. I would use 3D printing for a prototype only. The best way IMO is to have a mild made with a 5 axis or a machined EDM electrode.

Edited December 14, 2015 by Mitch Fields

[Mr Ben]

"Obviously a lengthy read, only really of interest to those thinking about using RP or WANTING AN ALTERNATIVE TO SLEEPING PILLS ."

As a vet with a nasty sleeping disorder, I can certainly appreciate this statement because It's just SO DERN FUNNY!

Of course you realize that to be absolutely certain of this, I'll have to sleep on it! ;-) (wink wink, nod nod, nudge nudge)

Hoping to see how things work out with the 3D interest. Keep us updated by all means. I just might have use for such nefarious skills (muahhahahahaha)

Wish I had the cash to invest in such a venture. (I wouldn't run the business but it would be fun and adventurous to learn new ideas, not to mention the profit potential.)

Edited August 10, 2016 by Mr Ben

[Vodkaman]

I am getting to a point were I am seriously considering the investment. Lures is only a small part of it though, but outsourcing the printing is just too costly.

 

I am toying with a new, light design of a bicycle frame, but to print it out, it would have to be in something like 16 pieces that plug together. But it is a prototype, NOT a saleable item.

 

Having my own RP printer would open up a lot of ideas that previously would have been extremely expensive to prototype and so the ideas collect virtual dust.

 

Dave

[mark poulson]

Dave,

Did you ever figure out how they print out assemblies, like your "ball within a ball"?

[Vodkaman]

Yes - They obviously can't print starting in thin air, so the assemblies are actually joined with thin filaments. These are easily broken when the joint is forced to move for the first time.

 

Another example - if you are printing a sphere: at the start, the overhang is too great and cannot be printed. The post processor takes the sphere model and adds in support pieces that after printing can be cleaned off. This applies to any structure with overhangs.

 

This is were the designer must have knowledge of the manufacturing process and design accordingly. There are many examples of the difference between drawing a part and designing a part. Here are three examples:

 

Mold design - the sides of the part must have draft angle, so the part can be removed from the mold.

 

spot weld design - the parts to be welded must allow access to the spot welder.

 

Bolted design - the parts to be bolted must allow access to the bolting tools/spanners/sockets.

 

Dave

Edited August 20, 2016 by Vodkaman