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Forearm Rubber Piece


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Well, as an active participant in this community, I figure it is time to do my part. There has been some discussion on acceptable glove designs and one of the pieces it the gray rubber piece at the top of the glove. Some of the designs have shown the indented lines in the rubber piece to be all curved in one direction. After watching some of the BARC scenes again last night, it appears to me that the lines take a different pattern. I've tried to illistrate this in my weak attempt to draw this on my work computer.

 

rubberpiece.jpg

 

I am looking to make these pieces out of sylicone rubber. I am currently trying to mold this piece out of clay so that I can take a good cast of the gray rubber forearm piece. The first thing I've discovered, I am not very good at sculpting with clay. :rolleyes: I will post my WIP as I go. Wish me luck. I am hoping to make a piece that I can mass produce.

 

If someone is already working on this piece, let me know and I will save my efforts for something else.

 

DaVe

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It seems you are right on the curve issue but we both neglected one detail. I'm going to illiustrate what I mean. Might take a while.

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I think the proportions are like these (a bit broader than your's in relation):

 

ribpad.gif

 

The stupid thing is that the part is not attached on but actually sits within the gauntlet surface which makes it more difficult for us. The dottet line in the bottom side cut graphic might be a possibility to place it in a possible hole in the leather and then sew it on using the extended outlining overlap on the bottom. Very complicated but I'd try it :).

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I think the proportions are like these (a bit broader than your's in relation):

 

ribpad.gif

 

The stupid thing is that the part is not attached on but actually sits within the gauntlet surface which makes it more difficult for us. The dottet line in the bottom side cut graphic might be a possibility to place it in a possible hole in the leather and then sew it on using the extended outlining overlap on the bottom. Very complicated but I'd try it :).

 

 

Mad if its recessed into the glove. Then what about cutting out the opening for it and sewing it into place to keep from moving around and the leather peeling back away from it?

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The stupid thing is that the part is not attached on but actually sits within the gauntlet surface which makes it more difficult for us. The dottet line in the bottom side cut graphic might be a possibility to place it in a possible hole in the leather and then sew it on using the extended outlining overlap on the bottom. Very complicated but I'd try it :).

I think you nailed the design perfectly... Again, my clay sculpting skills really need some work. My plan is exactly what you just said... fabricate a lip (.5" to 1") around the outside of the piece. Then I would cut a hole in the leather and attach it from the underside. I'm thinking a strong flexible glue like E6000 instead of sewing. I'm also planning on adding some padding (1/4" to 3/8" foam) under that cuff to get the fuller forearm look. My gloves should arrive tomorrow.

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Seems we are on the same track :) I've also experimented with foam to get the correct look. Leather I have already. I'm looking forward to your sculpt :) - won't be easy with these lips

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Seems we are on the same track :) I've also experimented with foam to get the correct look. Leather I have already. I'm looking forward to your sculpt :) - won't be easy with these lips

 

 

Make pattern for it then trace your hole out and cut it out. I would alos cut it out just slightly smaller then what you traced. Can't wait to see this.

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  • 1 month later...
  • 3 weeks later...

WIP pics...

P80001_resize.jpgP80006_resize.jpg

 

I'm not overly crazy about the way the plaster mold turned out. There appear to have been some air bubbles in the mold, but I might be able to trim those off the cast, kinda like trimming flash. Still think I can get a good cast rubber pull from my mold. It should be good for 10' accuracy, if not better.

 

Can anyone suggest a good silicone rubber to purchase?

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  • 1 month later...
I'm not overly crazy about the way the plaster mold turned out. There appear to have been some air bubbles in the mold, but I might be able to trim those off the cast, kinda like trimming flash. Still think I can get a good cast rubber pull from my mold. It should be good for 10' accuracy, if not better.

 

Can anyone suggest a good silicone rubber to purchase?

 

An RTV silicone would be good, but they can be very expensive, even just for a small kit of five pounds. It would be advisable that after you pour the silicone, to get it into some sort of pressure tank (ie a converted airbrush paint tank) for the duration of the cure. That would crush some of the air out of the casting. With the level mold you made, that would be ideal. Check out Alumilite's website for material options, or the Compleat Sculptor website for more expansive material details and prices.

 

Also, how flexible do you need the piece to be? If you start looking at the data sheets, look for a "Durometer" with the range of 55A to 65A. The "A" is very important because it denotes a softer shore... more flexible, rubber like. "D" is a much more rigid shore, like ABS plastic.

 

Sorry I'm a little late with this... but you could try a urethane based rubber. It would be much cheaper than the the RTV silicone. The only problem you would encounter would be what color you need the part to be. Some of the urethanes have a natural color. The range from a black, to dark brown, to a "buff" color. If you needed something more specific, colorant can be added to the urethane to match close to what you need.

 

If you need more information, or help, let me know. I cast urethanes day in and day out.

 

-fk

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Colour is a light-to-mid-grey. I thought it's possible to use pigments with PU?

 

PU? :( I'm lost....

 

There are several clear urethanes that are excellent for adding colour to, and they'll have excellent UV stability. You can add colour to silicones, BUT they should be formulated for use in silicone. Depending on the type of silicone, it could "sweat" the pigment out. I've made the mistake of adding a urethane pigment to a silicone. It's not pretty.

 

Most of the rubber urethanes I've used are from BJB Enterprises. I think there are several very good companies in the UK that make similar products. You might be able to purchase through them easier than overseas.

 

-fk

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Ok, my fault - I was talkig of poly urethane not silicone. Actually I don't like silicone though I have to admit I have no idea how many different types there are. My scarce experience with silicone comes from LARP where people use silicone coating for their foam weapons and armors etc. I've had a mask made of foam and silicone silver coloured and it was just ugly regarding the surfacial qualities.

So I thought poly urethane being available in so many different consistencies would be the better choice but i'm open to some lectures of an expert in this field :)

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heheheh... sorry...Polyurethane! or Urethane for short. :lol: Okay now I feel slightly dumb.

 

Yes, you can add colour to polyurethanes. Just make sure that the colourant you want to add will not inhibit the chemical reaction.

 

But, you CANNOT paint the RUBBER LIKE URETHANES. The paint, even if its acrylic, polyurethane based, will crack and peel off of the part. I should know... I've used and tested over 600 different types of urethanes available. You just know what you can and cannot do with this amazing stuff!

 

Yes it is a VERY good choice to make short runs of parts that need to be plastic or rubber like. :):D

 

My RECOMMENDATION: GO POLYURETHANE!

For this project, I would recommend getting a Clear (transparent), rubber like (Shore A, durometer rating of 55A-65A), and a colourant that is close to the color you need, or slightly darker, from the same manufacturer as the polyurethane.

 

:)

 

-fk

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Hey everyone,

 

Here is my WIP pics... Earlier I posted my clay model and my plaster mold. Here are pictures of my rubber casting.

 

I purchased the smallest sized package of Smooth-On's VytaFlex 40 and some of their black urethane rubber dye.

 

RUBBER0001a_resize.jpg

 

I measured out 3 oz. of part A and part B (6 oz total) and prepared my mix. Once I was happy with the consistency of the liquid rubber, I slowly poured it into my mold. The VytaFlex very easily filled all the parts of my mold. I over estimated on my required materials. 2 oz of each part probably would have been plenty.

 

RUBBER0004a_resize.jpg

 

After curing overnight, I was able to peal the rubber cast from the mold.

 

RUBBER0005a_resize.jpg

 

The rubber made a complete cure with the plaster. No tacky parts or uncured rubber. If you notice, I'd made a lip around the outside of the piece to attach to the inside of my gauntlet.

 

More pics soon... Please offer constructive criticism and comments. It is the only way that I will get better at this.

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Hey everyone,

 

Here is my WIP pics... Earlier I posted my clay model and my plaster mold. Here are pictures of my rubber casting.

 

I purchased the smallest sized package of Smooth-On's VytaFlex 40 and some of their black urethane rubber dye.

 

RUBBER0001a_resize.jpg

 

I measured out 3 oz. of part A and part B (6 oz total) and prepared my mix. Once I was happy with the consistency of the liquid rubber, I slowly poured it into my mold. The VytaFlex very easily filled all the parts of my mold. I over estimated on my required materials. 2 oz of each part probably would have been plenty.

 

RUBBER0004a_resize.jpg

 

After curing overnight, I was able to peal the rubber cast from the mold.

 

RUBBER0005a_resize.jpg

 

The rubber made a complete cure with the plaster. No tacky parts or uncured rubber. If you notice, I'd made a lip around the outside of the piece to attach to the inside of my gauntlet.

 

More pics soon... Please offer constructive criticism and comments. It is the only way that I will get better at this.

 

Dave,

the cast is in reverse, did you want to do it this way with the ridges recessed as opposed to protuding ?

In other words your pic of the black cast should be the mold in which you pour the rubber to achieve the "raised" ridges.

LMK

~Mike

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Dave,

the cast is in reverse, did you want to do it this way with the ridges recessed as opposed to protuding ?

In other words your pic of the black cast should be the mold in which you pour the rubber to achieve the "raised" ridges.

LMK

~Mike

Hey Mike,

I went off the design that Madphisto had posted earlier in this thread. The plaster was my mold and the black rubber is my cast / finished piece. The outer rim is raised highest, then the inner lines are "recessed". If the inner lines are supposed to be raised, I have to go back to the clay and start all over. It might be the picture angle, but the basic shape follows Madphisto's drawing.

 

I would have liked to have gone more gray, but the black dye was stronger than I expected. Nothing a gray wash can't fix.

DaVe

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DaVe,

 

Instead of making a clay master, try making the master out of styrene, or some other plastic. You'll get much crisper edges.

 

Before you pour the plaster on top of it, thin down some vaseline with some rubbing alcohol, and "paint" a thin layer all over the part. It will make it easier to take it off the plaster after it's done curing.

-fk

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DaVe,

 

Instead of making a clay master, try making the master out of styrene, or some other plastic. You'll get much crisper edges.

 

Before you pour the plaster on top of it, thin down some vaseline with some rubbing alcohol, and "paint" a thin layer all over the part. It will make it easier to take it off the plaster after it's done curing.

-fk

 

Yeah, the rubber will pick up EVERY bump, marking and defect you don't want. I only mention this because the rubber is rather expensive to use to have to do things twice - I know from expierence...

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