Wet molding / Prototype Mold

[Webicons]

Hello folks - I am attempting to wet mold a large valet.  This will be my first attempt at something larger than a pack of cigarettes so I'm a little hesitant. 

The dimensions are approximately 6 x 8 x 1.5 high. 

Before I waste perfectly good leather I wanted to run the design across you in an attempt to correct anything that may be an issue.

My main concerns are the corners and the steep slope. 

Thoughts?

 

 

[Rockoboy]

Never having done much wet-moulding, I think the steep slope, rather than a square corner, should make the whole process easier.

[fredk]

You'll have problems with the corners. I think the vertical ones will bulge out awkwardly. Better to have curved corners at all junctions

[Webicons]

21 minutes ago, fredk said:

You'll have problems with the corners. I think the vertical ones will bulge out awkwardly. Better to have curved corners at all junctions

Thanks.  So better to round off all corners?  

[Webicons]

So I took some time to round off the hard corners.  Tomorrow I’ll work on the frame.

Funny, if you told me that I would need to sculpt for leathercraft when I first started, I would have laughed.   

[alpha2]

Yeah, there's a whole lotta stuff that I didn't think I'd need to know when I got into leathercraft. For instance, I've got a 3000 dollar sewing machine on the way. Didn't see THAT coming!!!

Edit, the machine wasn't 3 grand...there was shipping, additional thread, bobbins, etc, etc. etc...

Edited February 1, 2018 by alpha2

[Webicons]

9 hours ago, Rockoboy said:

I think the steep slope, rather than a square corner, should make the whole process easier.

Thanks Rocko - trying to work through this one step by step.  I would think that the slope would make it easier too but leather likes to do its own thing sometimes.  

[Webicons]

54 minutes ago, alpha2 said:

I've got a 3000 dollar sewing machine on the way. Didn't see THAT coming!!

Nice!  You need to post a review when you get it in.  Looking forward to that day when:

1. I have enough work to justify a machine and

2.  Have $3000 banked! 

[Webicons]

Hello folks - Well this is the first pull from the mold.  The mold needs some cleaning up but I’m not disappointed with the tray.  It was made with two 2/4 oz Buttero leather back to back.

I just need to cement them together, trim, stitch, crease and edge paint. 

Note to self: 

    1.    don’t use the PVC board.  It isn’t rigid enough and doesn’t sand well (I had to remake it).

    2.    1.5 inches deep is a bit too much for a tray.   Makes more like a bowl (unless that’s what you want).

    3.     Use more clamps than you think you need.

    4.    Need to seal up the wood with some lacquer.  

The negative mold is pretty warped now.  Will this affect the next use?  What do you guys do with the warp? Any pointers to improve overall?

[fredk]

That looks very nice.

Warped mould? scrap it. Its not worth the heartache and cost of wasted leather if it doesn't do the job properly now

[kiwican]

On 31/01/2018 at 7:33 PM, alpha2 said:

Yeah, there's a whole lotta stuff that I didn't think I'd need to know when I got into leathercraft. For instance, I've got a 3000 dollar sewing machine on the way. Didn't see THAT coming!!!

Edit, the machine wasn't 3 grand...there was shipping, additional thread, bobbins, etc, etc. etc...

Etc etc etc. That sums up leather working pretty well

[Webicons]

22 minutes ago, fredk said:

Warped mould? scrap it.

Yeah.  That’s too bad.  I was hoping to fine tune the mold as it bites into the leather in some places but you’re right:  it’s not worth the ruined leather. 

[kiwican]

Make use of the warp. Add more (depending on where it is and how much it's warped). There is a market for asemetrical bowls and trays too.

[fredk]

What way has the mould warped?

Photos please

[Webicons]

Well to wrap this thread up here’s a pic of the finished tray.  Its not exactly what I had in mind but satisfied nonetheless.  

Few things more that I learned:

1.  The wet molded leather sews differently than the virgin material.  It was definitely more dense.  I had to awl sew the whole thing.  Pricking chisels just didn’t cut it (literally). 

2.  Next time I make a mold I’ll try to include as many reference marks as I can. I think I could have marked a stitching line and trim outline on the mold and it should transfer to the leather well enough.  Dealing with making them on a 3D shape is less than perfect.

3.  Use birch plywood next time for the base and frame.  

4.  Even the smallest cracks transfers to the leather. Wood filler should take care of that. 

5.  Take more time making the frame.  It’s just as important as the positive mold. 

Thanks for everyone’s help!

 

[Bigfoote]

Nice job, great stitching! The next one will be better! Always learning and improving.

[RockyAussie]

I think that is very good @Webicons and I think you reduce a lot of your waste than you are at present. You may some of the info in this post I did awhile back of interest. I found I got my waste on these handcuff pouches down to less than 1/4" and if anything I would say the results were better. Also on the top mould having a relief groove just past the cut off point helps the forming. Brian

 

[Webicons]

Thanks @Bigfoote!  I am a personal believer of the "practice makes perfect" mantra.  I have already started on my next mold and using what I've learned from this first one, I'm excited on how it will come out. 

Much appreciated @RockyAussie.  I've been following your threads and they gave me courage to give the larger items a shot.  Regarding your comment on the relief line:  When you say that it helps, are you talking about having a line to reference when trimming the piece or does it actually help with the leather molding itself (to make it more secure?)  I have access to a 3D printer and I was going to go that route but my Sketchup skills are lacking and I was concerned of patterning.  Did you sand the mold pieces smooth?

[RockyAussie]

7 hours ago, Webicons said:

Regarding your comment on the relief line:  When you say that it helps, are you talking about having a line to reference when trimming the piece or does it actually help with the leather molding itself (to make it more secure?)  I have access to a 3D printer and I was going to go that route but my Sketchup skills are lacking and I was concerned of patterning.  Did you sand the mold pieces smooth?

There is a lot of theory in coming up with that relief line, and some advantages are as follows. 1 - to reduce the waste when pushing down the top mould it helps create a little drag and keep things tight. 2- As the leather is trying to compress everywhere and on particular the corners, the relief gives the leather somewhere else to go beside just sideways and thereby reduces the wrinkles. 3 - It gives a very nice and reliably accurate cut off point to cut and sand to. I did sand the mould pieces a bit but mostly just rubbed the edges very hard with a rounded steel rod in order to achieve maximum smoothness. On large scale pieces a printer may not be the best answer always as the time to print can be very long but can allow a lot of fancy details to be embedded if that is desired. CNC routing/milling can be a better alternative at times. The big advantage with using the cad design start is being able to come back and easily make minuscule changes and corrections in a very quick way. At least the printer can print it again while I am getting other work done. For anyone interested in wet forming leather I recommend looking at a couple of this mans videos. To me it is amazing and I am sure you will be inspired by them. Brian

 

[Kenl]

I would be interested in hearing more about the glue up process of the two pieces. And at what stage of making the two pieces do you glue them up. Type of glue? If you don't mind sharing. Thanks Ken

[Webicons]

33 minutes ago, Kenl said:

And at what stage of making the two pieces do you glue them up. Type of glue? 

After popping the leather out of the mold I did a rough trim about half an inch from the final edge and glued it together using Weldwood contact cement.  

I only applied glue at the edges because I was concerned about messing up while joining the pieces together (ie misaligned pieces). 

I then proceeded to trim the whole piece to final dimensions.  

 

[Webicons]

Thank you @RockyAussie.  That’s a lot of great information.  I can appreciate the thought that went into making your molds and I hope to apply these tips on my next mold. 

I was salivating watching the CNC do its work on the video.  It’s definitely on my list of dream tools to get.  If only I could justify it.  I do, however, have access to a Bridgeport mill and the video gave me the idea to use Delrin instead of wood as the dust wouldn’t be so good on the mill.

Thanks again

[Kenl]

Great thanks for the information. I have been wanting to make multi layer bowls and glad to hear how someone else is doing it. Thanks for sharing.

[Webicons]

34 minutes ago, Kenl said:

I have been wanting to make multi layer bowls

I saw one of your post regarding glueing up while wet. Keep in mind that the leather shifts and shrinks during the molding process so  best to apply the glue after the pieces dry.  

On a double sided bowl I would recommend molding both pieces at the same time so the offset is already built in to the piece.  

Cant wait to see it complete.  Please post when done. 

[Kenl]

Thanks for the heads up. Any tips are welcomed.