First seams – how to tell if it’s good?

[xraymtb]

Started attaching 3R today (Skeena build). It seemed to go ok but the tube material isn’t uniformly darker across the entire seam (some parts are darker with a shine – others are less so). Not sure if this is ok or if I need to do more?

Also seem to have overheated the bottom TPU slightly in one area. I’m thinking it’s fine on both counts but would appreciate anyone with experience commenting?

I did some tests prior to this, have made the inflation bag and seat, and all seemed to be ok with those. Maybe I’m just being overly cautious?

Topic

[ejensen]

Just got my kit and now have scraps to try out. Using the Aliexpress leather iron at max setting. I found that a test strip of 250GSM (tube fabric) on  450GSM (floor fabric) would separate by the TPU peeling off the floor fabric (see photo)

Joining 250-250 resulted in a very strong bond that eventually tore with some TPU on each side. Joining 450-450 was tricky as the matte side seemed to stick to the iron so used parchment paper. The heavy stuff took longer to heat, but after cooling came off all on one side.

It feels like the TPU comes off more easily on the heavier stock (black 450GSM material). Does that sound right?

[Matt (Admin)]

Yep, that sounds about right (see the “Note” about sealing different fabrics together on the Heat Sealing page). You don’t need to join 450 to 450 in any of my designs, so don’t worry about that. Cheers!

[Barbara]

Here’s my first trial seam, done on the fabric swatch set (210d and 420d).  When pulling it apart, all the TPU came off on one side (yellow 210d).  I’m feeling pretty good about this, but thought I’d check in before tackling a Skeena.  How does it look?

Also, just curious if we know what the melting point of the fabric is, i.e., how much of a range in temperature could be used on the iron.  Is it polyesther (melting point 295°C) or nylon (melting point 256°C)?

• This reply was modified 3 years, 9 months ago by Barbara.
• This reply was modified 3 years, 9 months ago by Barbara.

[Matt (Admin)]

Looks good from here (see the “note” on the Heat Sealing page about sealing different fabrics together).

It’s nylon.

[xraymtb]

[Matt (Admin)]

Hi – your pictures didn’t seem to work (I just see an “image not found” icon), but from what you’ve written it sounds like it’s probably fine. I designed the seams to be way more than wide enough, so even if they’re not perfectly sealed they will be strong enough, within reason. Cheers!

[xraymtb]

Thanks. I’ve tried adding pics again although they don’t show much. I’ll get on with the build and keep my fingers crossed!

[Matt (Admin)]

I see them now – it looks like your iron might be a bit too hot, but it’s hard to tell in the pictures. I don’t normally see the woven fabric get shiny like that. (What I see doesn’t look like a problem though.) The fabric shouldn’t melt at all, just the TPU. Lowering the temperature a bit will also reduce the chance of it melting through to the bottom of the floor – just be sure to test some scraps whenever you change the temperature.

[Author]

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