Rapid prototyping, which process to use?

[LeMarchand]

This year i want to use a rapid prototyping service to print a prop for me i have made as a 3d model. I am thinking SLA but there seem to be so many different services and the finish on the parts i have seen seems to differ a lot.

I am looking for a process where the cleanup is minimal and the surface is a smooth as possible, so not the 'powdered sugar' surface. I have seen SLA parts that look really clean.

So, where do i go and what prototyping process would be best for my project,

Here's some pics of the prop and the prop broken up in the individual parts. And yes.....i know it will cost me close to 1500-2000 bucks to have it done

 

[Darkside]

Stereolithography

costly but minimal work afterwards and nice finish
mostly clear or white material.

 

[LeMarchand]

you mean SLA right? Are there different types as a lot of the parts i have seen have that rough surface.

would sandblasting be a good way to smooth the surface?

 

[Anakin Starkiller]

you mean SLA right? Are there different types as a lot of the parts i have seen have that rough surface.

would sandblasting be a good way to smooth the surface?

As I understand it .certain rapid prototypes would be blown apart by sandblasting. And either way, sandblasting doesn't leave a piece smooth as much as it leaves it uniformly rough (like sandpaper almost). Sort of a uniform rough grey textural finish.

Dan

 

[DaddyfromNaboo]

Marc,

it really depends on what you want to pay for the pieces you need.

The best would be a metal piece milled by a 5-axis cnc mill. smooth as heck and ready to mold.

THe way I went with my Typho blaster was a compromise between quality and price and speedy delivery I am really happy with it, although I still have to do a lot of work on it, including figuring out the best way to smooth out the surface. Next try will be several layers of spray on filler.

Michael

 

[CustomCreations]

id def get a CNC quote. Ive used SLA and it takes ALOT of cleaning up- plus I find it does have a certain 'memory' to it which means your lines tend to re-appear after spraying. Small details can be fragile if the part isnt built in the right position on the bed.
Nice CAD work- is it Rhino?.
PS I know of a company in the far east, run by a UK guy, who quoted me 1500 for a full size Dredd Lawgiver- built in parts like yours, CNC'd,and ready for paint. I didnt go for it cos I didnt have the $$££ though ;-(. Depend on your view of going outside the US too I guess !

 

[LeMarchand]

id def get a CNC quote. Ive used SLA and it takes ALOT of cleaning up- plus I find it does have a certain 'memory' to it which means your lines tend to re-appear after spraying. Small details can be fragile if the part isnt built in the right position on the bed.
Nice CAD work- is it Rhino?.
PS I know of a company in the far east, run by a UK guy, who quoted me 1500 for a full size Dredd Lawgiver- built in parts like yours, CNC'd,and ready for paint. I didnt go for it cos I didnt have the $$££ though ;-(. Depend on your view of going outside the US too I guess !

Well, i guess i could never hurt to get a quote from your guy in the far east, so if you can send me the contact info for them, that would be highky appreciated

I indeed use Rhino, as a total 3D modelling newb, it turned out to be a very user friendly program although i still suck at organic shapes

thanks people

 

[noble]

I've been finishing RP parts for several years now, and have a few suggestions.

-Lightly sand the parts before you primer them.

-Use a Catalyzed Primer sprayed via hvlp gun. (your lines won't show)

-Only use rattle can primer for touch ups.


Sandblasting would destroy the part. Stay away from the starch + wax printers. CNC won't get all your minute details. All your little indents appear
to be really small.

I've seen SLS parts that look very nice.

Check out that technology.

 

[exoray]

CNC won't get all your minute details. All your little indents appear to be really small.

Unless I'm missing something there doesn't appear to be anything too small for a mill...

I was recently given a private tour of a fully equipped aerospace certified machine shop and shown some satellite and missile parts that were mocked up in aluminum prior to a being machined in titanium and I was blown away with what the proper equipment can do... Fine details are hardly a problem...

I say if the design is final and and it's cost effective (or within your budget) get a CNC one done... The biggest drawback to having it done on a 5 axis is paying the guy to do the machine programming and setup vs a rapid prototype that simply prints it from the files...

 

[JOATRASH FX]

I've been through some of these issues already with my Vera/Alice project (see my sig.). You do have a few complex shapes and small details there, but I concur that a good machine shop should be able to handle them, though you might need to combine or separate some parts.

I can't help you out with what RP material to use, but I can say that I doubt you'll find a CNC machine shop in the US or Europe that will do only one set of those parts for as little as $2K. At least not if you just shop around for quotes. CNC work is horrendously expensive when you want to do just one or two copies of a part. (The highest quote I got for my set of Alice parts was $8000-$11000! I kid you not.)

However, that doesn't mean it's impossible. There are quite a few machinists on the RPF that might be able to help. Otherwise, what I suggest you do is check locally, starting with your own home town and working outwards, to see what companies do CNC. Once you get a few names, do a little checking and see of you can find out who is "shop manager". (You want to find someone who is "close to the floor" and not in a purely administrative position. Write a courteous letter to this person explaining your project and ask if they can help- maybe one of their machinists likes to take on hobby projects in their spare time. The idea is to get someone interested in helping you out due to the uniqueness of the job. (A project like this can be an interesting diversion.) A small (10 man or less) shop is probably a better bet than a large corporation.

Send the letter (e-mail will do) along with some pictures, and a few blueprints. Give them a couple days and then phone them up. You'll either get an instant "sorry, can't help you" or if you're lucky, a "we might be able to help you if you're not in a hurry".

Or, if the shop is close by, you can pop in the car and go visit them. Nothing beats a face to face chat to make your excitement rub off. Sometimes, you can find someone willing to do it when they have free time, or when it's a slow month (rare for CNC shops these days).

Be prepared for a few letdowns... but don't give up and be prepared to wait a few months to get all the parts. My entire project will most likely have taken almost a year before it's done. I had to shop around a couple months and talk to a lot of people before I found a guy willing to do mine. I had more than one guy underestimate how much work there was. I finally lucked out and found someone that was enthused about the whole thing and even knowledgeable about guns. It's taking a lot longer than I'd have wanted to get the parts made, (my machinist tries to find time for them in between doing parts for jet engines and such) but they are being done.

Heh... I just realized this all reads like trying to get a job in the film industry! :lol

May I ask... did you model the parts as SOLIDS? (or meshes? NURBS?) If they're not solids, you might have a hard time using your files (and as I learned the painfully time consuming way, meshes don't convert to usable solids.) If you do go for RP, you could combine a few of the parts to maybe save some cost, unless you need them all separate for painting/molding. You'll probably need to export them into IGES or STEP format.

Whoa... long message. I'll stop now, but end by saying that when you finally see and hold one of the finished parts in your hand, the feeling is incredible. Please keep us up to date with your progress! :thumbsup

 

[CustomCreations]

good point- I hope you have checked the rino file for edges..........Ill PM you the far east guys
Dan

 

[noble]

Unless I'm missing something there doesn't appear to be anything too small for a mill...

Depends on on how small the shop milling bit is, and really small bits can't reach deep areas. Just a suggest though. Not saying it won't turn out at all.


Another important suggestion, Your building a solid part. The cost of RP is

cubic inches of the part and machine time. Since your using Rhino, I suggest

using some offset commands to make hollow areas on larger parts to decrease

the cubic volume and save you some dough. If you keep the wall thickness

around 3-4mm, you should be okay and your prop won't be to heavy.


As far as the iges file deal, It is a pain in the butt to take a nurbs file into
a solids program. You have to stitch + repair edges and faces. A true pain.

You won't have to worry about that if you do the RP printing. Rhino can
save directly to STL format. That is what format you'll need for printing.
Just make sure your resolution is high. (.001 or greater)

But, if you go the CNC route, you'll have to save to IGES format and go through a program like MasterCam. Probably going to be a pain.

 

[Ramiel]

Well Marc,
I hope you'll find a way to do it, because I want one soooo bad!

 

[LeMarchand]

I'll probably will be using several processes for it after reading the replies. The grip is a piece that would either require 5-axis machining or SLA, some stuff can be done on a lathe, a lot can be done on a 3 and/or 4 axis mill.

I'll contact the 'far east' company and see if they can help out.