what to use as a cheap material for a prototype

[Piero]

Hi Guys

I am wishing to try and see if a idea of mine will work and wish to build a prototype out of cheap easy to machine what ever!!!!

if all goes well and after much playing with the design, id like to end up making a one off suspention swing arm for a old classic vespa

so for now, I will probbably be making a few prototypes and dont want to invest a lot of money in each

what would you use to the prototypes ????

Not keen on the idea of wood as I have never (nor do I wish to) used wood on my metal lathe or milling machines

 

[garethp]

I've never used the stuff but if you google 'prototyping foam' you'll get relevant results

 

[Piero]

just had a look.

looks very messy to me lol

i have loads of alluminium off cuts,

what would I need to make a ingot

obviously not for the finnished item but just so I can machine it and make the prototype

 

[Ruffian]

3d printing??

 

[Piero]

yeah 3d printing would work only I dont have one,

 

[Tangledfeet]

Wood?

 

[Piero]

i dont really want to use wood on my metal lathe and milling machine

 

[Mr shiney]

Engineering plastic. Delrin. I prototype everything in it. Easy to work with, you can take massive cuts out of it even on small machines, cheap and nice to work with.

 

[AndersK]

Cibatool is what you want. Available in different densities. The lightest is probably not so good for cnc machining and the heaviest is a little trickier to carve by hand.

 

[Hopefuldave]

Machinable wax? Melt candle wax (Hobbycraft sell it by the kilo) and dissolve in as much low-density polythene (carrier bags in a pinch, or shredded milk jugs) as you can, good idea NOT to do it over a flame! once dissolved, cast an ingot and practice machining on it, treat it like aluminium for feeds / speeds. If you need, you can "weld" it with a hot knife to join separate parts.

Dave H. (the other one)

 

[Screwdriver]

Machinable wax? Melt candle wax (Hobbycraft sell it by the kilo) and dissolve in as much low-density polythene (carrier bags in a pinch, or shredded milk jugs) as you can, good idea NOT to do it over a flame! once dissolved, cast an ingot and practice machining on it, treat it like aluminium for feeds / speeds. If you need, you can "weld" it with a hot knife to join separate parts.

Dave H. (the other one)

That sounds interesting. I just have to say, most milk jugs are in fact high density polyethylene (HDPE) as are most carrier bags. The really thin bags are LDPE.

Having said that, I'm interested in the idea but how do you melt HDPE to the point where it will combine with wax? I have played around with HDPE (I collect milk jugs!) but never considered the idea of effectively making an alloy. I have only ever melted them into a super thick goo, not a liquid. What method would you use to melt it and how do you then introduce the wax without it flashing over and bursting into flame?

<edit> Aha! Google has the answer. I think I have just found another project! Oh and something I can do with my milk bottle mountain. Google says just melt the wax and add the plastic, then stir. What could possibly go wrong?

 

[earthman]

Hi Guys

I am wishing to try and see if a idea of mine will work and wish to build a prototype out of cheap easy to machine what ever!!!!

if all goes well and after much playing with the design, id like to end up making a one off suspention swing arm for a old classic vespa

I'd like to see what you come up with but if you were to use delrin, wood, wax etc, how will any other these materials work in practice? I'm thinking of the forces/stress that a typical suspension component would be under,.......do you then plan on making a copy from metal to then fit to the scooter for further testing??

 

[Ruffian]

If you cad it I dont mind printing stuff.

 

[Screwdriver]

Delrin = not cheap!

If you just want to see how it looks, use a block of foam and build a hot wire cutter.

 

[Piero]

ive welded a few scraps of ali togeather and will use that

One important aspec for me is also the machine work, ill learn a bit more actully making it from the same marterial as I will end up making the proper one from

 

[brightspark]

i dont really want to use wood on my metal lathe and milling machine

why not its not as bad as cast iron and you can cover most of it up

 

[stuvy]

Keep us updated I love things like this

What model is it for? What’s the advantage of yours over a standard item?

 

[Screwdriver]

why not its not as bad as cast iron and you can cover most of it up

...and mahogany turns beautifully. Other woods are available but I came across a stack of mahogany window frames in a skip so...

 

[bigegg]

That sounds interesting. I just have to say, most milk jugs are in fact high density polyethylene (HDPE) as are most carrier bags. The really thin bags are LDPE.

Having said that, I'm interested in the idea but how do you melt HDPE to the point where it will combine with wax? I have played around with HDPE (I collect milk jugs!) but never considered the idea of effectively making an alloy. I have only ever melted them into a super thick goo, not a liquid. What method would you use to melt it and how do you then introduce the wax without it flashing over and bursting into flame?

<edit> Aha! Google has the answer. I think I have just found another project! Oh and something I can do with my milk bottle mountain. Google says just melt the wax and add the plastic, then stir. What could possibly go wrong?

melt the wax over a pan of water.
preferably outside.
safe enough if you are careful

 

[Kram]

Most of these are as expensive as the real thing, particially as one offs where you wont be buying a full length/sheet. What sort of size are you talking?

Welded steel plate probably cheapest, tho that will be a very different construction to cnc aluminium.
Id look at what can be reused. Aluminium, waxes and plastics can often be remelted, aluminium the best option if somone local has the ability to cast for you. I have plenty of scrap and have been attempting to do it myself last year - not easy!