how best to make this small run handle

[chookie]

Hi all!

Hoping one of you will be able to help us out with some advice.

We are a small manufacturer in Australia, so far not doing anything with plastics, but that's about to change! We currently make a product used for tagging fish, same basic idea as a screwdriver.

It's a (currently made out of wood)handle about 4 inches long and 1/2 inch diametre, slightly tapered. It has a hole up the middle into which we glue a bit of 3 mm ss tube.

We need to look at changing this design so the handle is made out of plastic of some kind (preferably black). The trouble comes in with it being a small run, we'd probably only need 100 at a time as they usually sell in lots of 20 and aren't heavily marketed at the present.

we have a reasonable workshop set up here but have no experience with plastic molds. Am assuming we're looking at an injection mold solution, but if we outsource our quantities are too small? Is there a way to do this ourselves? It is such a bloody simple thing, but it's hard to know the right avenue to take, diy or ??????

Any feedback in terms of solutions / materials is GREATLY appreciated.

Many thanks,
Chris

 

[insideman]

Injection molding does not look like a solution. Quantity is too small. You mention a taper. Can you get rid of this feature? If so, the door opens to making it out of tube or rod, which should be available at plastic supply houses.

Possible materials include acrylic and ABS. Both can be easily machined.

 

[patprimmer]

I can put you in contact with moulders who will mould 100 off, in any capital city in Australia, and in quite a few major regional towns on the east coast. The problem will be tooling cost. Even a simple plastics mould cost a few thousand dollars, and unless you know something about them, they are beyond the scope of the DIYers.

If you send me a sample or a drawing, I could ask around to see if someone has something similar. For instance, the handle for the Lewmar or Titan plastic handle for yacht winches is moulded in Sydney.

Other possibilities for low volume are rapid prototyping techniques like stereo lithography models or casting resins like thermoset polyester, cast nylon, cast acrylic, cast polyurethane, or epoxy.

I can put you in contact with an old colleague who specialises in rapid prototyping. He is based in Qld, but regularly travels around Aus and NZ.

Regards
pat pprimmer@acay.com.au
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[chookie]

Thanks so much guys for your help!

At the moment we have our wood version on the way to a plastics place that deals with rods and sheets, they've got the right size nylon rods (or other types)and tell us no worries to taper and drill hole up the middle. They say 100 off no trouble doing it for a good price so we're waiting for the quote.

Thanks, you're feedback helped us to think around our original ideas.

All the best!

Chris

 

[MouseTrap]

Sounds to me like you want to look into 'polyurethane casting'. This process is well suited for quantities such as you mention. Some of the shops that do this are very small, hence very little overhead is involved.

Find a couple of polyurethane casting houses in your neck of the woods and begin dialogs with them.

You may be able to mold the small piece of stainless steel tubing right into the product (might require an added notch or something to insure the tube does not fall out). Note that polyurethane is a less 'glue-friendly' material than your current prototype which is wood.

I recommend that you create an engineering drawing (a good drawing) of your part complete with tolerances to use for purchasing (contract) purposes. An experienced mechanical designer with a plastics background should be capable of doing this for you.

Good Luck - Mousetrap

 

[chookie]

Thanks Mousetrap - will see how we go with the sample we sent. Thanks for your opionion re the Poly U, worth checking out if solution # 1 doesn't work.

Cheers!

 

[EvOne]

Before making a handle myself, I would try to look around and find a product already being produced that has the handle you are looking for and try to buy from that manufacturer. When I have the time, I often just wander around places like Home Depot, Lowes, Ace Hardware, Harbour Freight, etc and do what I call "wander shopping". Just kind of trying to catalog things for future projects. More often than not I either don't end up buying anything that day or I find something that solves a current problem on another project. Like the other day I was looking for a thermostat to use on an incubator and ended up buying some steel T-post for a goat pen I needed to build. Was planning to use tubing @ $8.00 per unit/length, a slight redesign and the T-post was a perfect solution for $3.50 ea. Barring a quick fortuitious find I think the earlier post about moulding your own out of PU is a keeper.