Mold making

[firehawk7]

I am researching if I can make a mold to be able to produce a product faster in order to keep the cost down.

I am making custom gauge pods and have to make each one by hand and thought if there was a way to mold them I could cut the build time down and cost.

So I am looking for info or websites that can help figure out if these parts are able to be molded and what products to use.

Any help is appreciated.

I can post up what I am making but don't have one here with me now, I will later.

Thanks, Jay

 

[astroracer]

What are you making them out of? How complicated is the shape?
Making two part rubber molds is done all the time for resin casting model cars.

 

[dlcwent]

How about a picture?

 

[Retrosmith]

Take a look at smoothon.com

 

[firehawk7]

What are you making them out of? How complicated is the shape?
Making two part rubber molds is done all the time for resin casting model cars.

They are made of PVC and ABS and using hot glue to hold them together, at first I was wondering what I could use in place of the hot glue that will not be more expensive, then I thought of the mold making I have seen on Mythbusters. It is pretty complicated in my opinion for a mold but they can be made of a few different pieces.

The products need to be somewhat cheap in order for this to be feasible as I will not be making a ton of these(maybe 20??), I can trade $$$ in materials for $$$ in labor though so it can cost more in supplies as it does now.

I will post a picture later when I have them here.

How about a picture?

Working on it.

 

[firehawk7]

Here is a picture of it installed but it does not show the whole part.

 

[ggoss]

How about vacuum forming? You should be able to make a cheap rig using not much more than a plywood/mdf box/frame, shop vac (which you may already have), and a small space heater (or kitchen oven if you don't mind). It should work with polystyrene, PET, polycarbonate, ABs, and maybe a few others.

You can find a bunch of plans for building one with a quick Google search. To use it, you would need to make a positive mold of your gauge pod (a little smaller than the final product, as the plastic will be formed around it), but after that, you should be able to make another in just a few minutes, and for as cheap as the sheet of plastic it is made from. If you make several molds, you can make many at the same time depending on the size of your rig. This is how (I believe) most dashboards are made in the first place. A more common example is blister-packs on tools/kids toys/etc, though those are typically of thinner plastic than you probably want to use.

 

[Barlow L]

I second smoothon.com. They will send you samples of the materials. Making molds is easy. If you have the skill to make those gauge pods, you'll pick up on it real quick.

 

[firehawk7]

Here is what I am making

 

[firehawk7]

I ordered some urethane resin to try while making these the way I have been.

I need to research how to make a mold for these first and if I accomplish that I will try pouring one.

I will look into the smoothon stuff too

Thanks, Jay

 

[Zeke]

Why do you need a mold for only 20 items? Continue making those out of PVC or ABS pipe and using the respective glues. If it's the base you are having trouble with maybe consider a redesign or using fiberglass lay up construction. For that you could make a simple mold out of wood, metal or plastic. You need to understand 'draft' when you build your mold.

BTW, I think those are damn clever being that you are shaping PVC pipe into something with style.

 

[chris fresh]

Liquid latex molds and alumilite,or alumilite molding materials and their product for casting.

 

[firehawk7]

Why do you need a mold for only 20 items? Continue making those out of PVC or ABS pipe and using the respective glues. If it's the base you are having trouble with maybe consider a redesign or using fiberglass lay up construction. For that you could make a simple mold out of wood, metal or plastic. You need to understand 'draft' when you build your mold.

BTW, I think those are damn clever being that you are shaping PVC pipe into something with style.

Just exploring my options. Could sell 2 could sell 100, the cheaper I can make them the more I can sell.

If it were a solid piece I would have ordered the stuff and just done it but with it being hollow I could not figure out how to accomplish that.

If nothing else I might learn a new craft as I have never made a mold before but understand the basics and watched a few videos.

 

[e-rockin-it]

I've used the smoothon urethane and silicone rubber molding stuff before it can work well but you need to follow the directions to the T.

Depending on the urethane you'll have to degass it or you'll end up with bubbles in the casting (ask me how I know). You can actually build a pretty quick de-gasser for not very much $$. I used a few air fittings and a vacuum pump that I use for AC work. I just hooked them to a glass mason jar type thing (I think it was a spaghetti jar from WalMart or something)

When you mix your ingredients you put them in this jar first, apply a vacuum and you'll be amazed at how many formerly invisible bubbles appear, and then when the foaming is done you do your casting.

I've designed a few parts for injection molding, and I've done some casting which is I believe what you're thinking. your part is probably going to be next to impossible to do as one part. If it was me I'd make a mold for the round parts, you can do a mold with 3 cavities or more if you want to speed up the process. I'd position the part with the large diameter facing down in the mold, and make 1 half of the mold cast the large diameter and 1 half cast the smaller diameter. This was you can position the parting line somewhere were you may not have to finish sand it afterwards (towards the back of where the large diameter meets the small diameter). You could then make another mold that you would put the 3 circular parts into and cast that block onto them. Judging from your pics you're already doing that though? But with urethane you should have a peg in each piece for the casting to mold around to form the block since new urethane won't want to stick to old urethane.

For making the parts easy to remove from the mold you would generally have a 3 degree draft angle on a part like this (it basically ends up looking like a cone) but can be done without it if you use a really tough silicone mold. You'll probably end up tearing through a few of the molds though since it looks like your part doesn't have a draft angle on it so in the end it might not be very cost effective to mold the parts, but at least you'll learn a new skill.

When we make masters for stuff like this at work, we usually have the master that the mold is going to be made from 3D printed (check out shapeways.com) for cheap, and I mean cheap 3D printing. I honestly can't figure out how they make money, I've had parts printed for me in the past that ended up going into the 1000's qty before we made a mold because it didn't make financial sense to tool up a real mold they were so cheap. Their finish on the cheap stuff isn't so great though, so for a master mold you usually end up spraying with high build primer and sanding until it's absolutely perfect. You may also find that you like the texture on your parts. I don't think I've ever done a part without texture since you see finger prints on them if you don't have at least some texture.

Hope some of my ramblings help. Good luck

 

[EdT]

I too make low-to-no volume parts and always wrestle with the tooling question. For the volume you are talking about, say<100 bezels, I think the way you're doing it makes sense depending on how long it takes you. If you are hand whittling each one, it's probably taking too long to do so making some jigs and fixtures to speed that up would be a good plan. Guessing from your comments that the bezels are made from PVC and ABS plumbing parts, I would sure look to something other than hot melt to glue it together. It really doesn't stick that well and most types do not sand or accept paint very well either. I'd suggest the plumbing glue that's made for both kinds of pipe or, even better, some methylene chloride solvent adhesive like they use on plastic models. You can get a little bottle at a hobby shop probably called liquid model cement and, if you need more, it can be had in larger containers from places that sell plastic material to commercial/ industrial businesses. I think I found some at McMaster-Carr too.
For the base part I think I would go with some ABS or PVC bar stock. It's very inexpensive compared to the time it takes to fab up something like that. You can probably put the round cutouts in with a hole saw or a big Forstner bit if you have a drill press and go real slow. The material will tend to melt in the saw cut and make a mess. Some holes drilled tangent to the cut line into the waste area can help the chips to escape and make things easier if you're using a hole saw. Could also be band sawn. Don't know what you have for tools.
You could make up a mold to do this as well, but for the volume you're thinking about, I don't think it's required unless you just want to do it that way to get the merit badge.

 

[kwb]

The shapes you have are not very good to have a parting line to be able to get the part out of a mold. You will need to redesign parts - how you redesign depends on what type of process.

A vac formed ABS sheet design is going to be quite a bit different than a pour in casting resin.

 

[GirlnAgarage]

What is your process? Are you building each pod to completion before starting the next? Are you using any jigs, fixtures or power tools now?

I don't think molding is the way to go on what you're currently building. If it were me (and I have built things from patterns for money), you just need to adjust your process from building one to completion to production line style. Possible a redesign on the mount bracket and back end to simplify the steps. (ETA: Relooked at your dash pics. I see why you designed it the way you did. Makes sense, though still wonder if that is the simplest form. But it is effective)

For the process, rough cut all your pieces at once so you have a box of whatever number you need, say 30. Example, that front bezel, chop 30 pieces to rough length. When finished, hole saw the front edge to achieve the curved hood on all 30 pieces. When that is done sand in the bevel using a drum or rounding sanding implement. Now you have your 30 front hood bezels.

Do the same for the gauge body. Do the same for the mount bracket. Only when you have all pieces do you start putting them together. Since each part was cut at the same time from the same jig/tool setup they should all measure the same.

Essentially you are stepping away from the one off custom to the production line. It'll speed up your building on these things ad create a more uniform product.

I saw hot glue mentioned up there. What piece are you using it on. It could be critical. Hot glue can dry out, crack and let go. Your customers will be pissed if that happens. Consider a better product or a redesign for that joint connection.

 

[Kevin54]

For making those, you don't need a mold. The block base can be machined as one piece. Making it out of some sourced plastic, machine time on that is maybe 20 minutes a piece after figuring the initial setup, getting the tools set and such. The other parts are what looks to be your PVC tubing. Again, with machining, you are only looking at a few minutes per each part to machine. All in all, for a 20 piece order. A good solid day at it on a machine, and you could have the components all ready. Some of the parts, instead of gluing could be press fit.

Check your PM's

 

[zr1nsx]

It's not a terribly difficult part to injection mold, but the design and construction of the mold would be in the $8,000 -$10,000 minimum range, so you would have sell quite a few parts to amortize the cost of tooling. I would look into someone who does additive rapid prototyping to see how competitive the price would be for 3D printing. Of course, you will need to have a CAD model in order to obtain pricing.

 

[Vegaman_Dan]

I think I'd make a two piece fiberglass mold and make my copies using resin and cloth in that mold. Very cheap to make, can be done fairly quickly. You'll have to clean up the parting lines, but you'll have to do that in any two piece mold you'll be making anyways.