Stitching Sole Bend Leather...

[CFDBattChief]

Greetings fellow leathercrafters,

Newbie to the group here, first post in hopes of getting some advice. I work at a leather shop where one of the items we make are the shields that go on the front of a firefighter's helmet. We use the very dense, thick sole leather, and on one of the types of shields we make we have to stitch a black leather backing to the sole leather. The leather backing is probably a 5-6 in thickness. We have a Cobra 4 machine, and I simply cannot get the machine to successfully stitch through the leather, even without the backing on it. We have the largest spear point needle that Leathermachine Company offers, a size 28 I believe, using 277 thread, casing the leather, and even applying some silicone oil to the needle, and still cannot keep the material from flagging, and in some cases pulling the needle from the machine. The top thread also frequently breaks.

We would like to be able to do this in-house now with the acquisition of this nice machine instead of having to farm out the stitching on this particular shield. Would anyone have any experience in doing something similar to this and could offer any suggestions?

[kgg]

I would give the Leather Machine Company a call, explaining in detail what is happening, what thread you are using, what needle size and type of needle also what you need the machine to sew. I am assuming you meant 5-6 oz leather backing not 5-6 in thickness of backing leather. 

kgg

[CFDBattChief]

Thank you, kgg. Yes, the "in" was literally the word "in", and not supposed to be an abbreviation of inch. I just left out the "oz" in my description.

I have called them, and have been working with Dave. We have tried all that I mentioned in the post which were suggestions from him. They have other customers doing what we are doing with the leather shields for helmets, but none of them are using the sole leather. We use the sole leather because it withstands the abuse of being on a helmet and lasts much longer than leather that isn't as thick.

I wanted to post the question out there to see if anyone else has any experience in doing what we would like to do. Here's an example of what we would like to be able to do in-house.

Edited January 24, 2019 by CFDBattChief

[Handstitched]

G'Day, 

Firstly, welcome the the forum  

Hoping that  I've got my conversions right, ( I work in milimetres here in Oz  )   your backing leather is approx 2- 2.5 mm? Sole bend, approx 5 - 6.0 mm ?  Thats 8.5mm .  We'll say 9mm total. 

I wouldn't have thought you'd have any problems sewing that thickness.I have virtually the same machine ( but different name) . I have attached a few pics of a  test piece that I did a long time ago, mainly for my own curiosity .They're a bit blurry, sorry.  

The test piece was  5  ( dry) layers of 4mm ( 10 oz)   D/S  = just slightly over 20mm, about 22mm when measured.  The machine sewed it no problem. However, I did go very slowly. The needle was understandably quite  warm when I finished.  

I use 277 M10   thread, and # 24 needle.

I've never had any jobs that require that thickness, but its good to know these awesome  machines are very capable of sewing it. But I would like to do harness work in the future.

But as for whats causing the problem, I don't know what suggest.  Maybe perhaps do a little test like I did. Sew some that is veg tan, some dyed, wet,  dry,  etc. A process of elimination? I haven't been much help.  Sorry  

HS 

[CFDBattChief]

Thank you for the reply, Handstitched. Yes, in mm, a sole bend is roughly 6.3 mm (1/4") thick, however it is the most stiff, dense, and hard leather that we use. It is mostly used I believe for making the soles of shoes, hence the name sole. We are making a little progress after having tried many different things. The dry leather actually seems to do better than if we try it while damp. I tried a spear point needle size of 28 using 277 bonded nylon thread, and even if I take it nice and slow, you can see the needle start to bow as it is forced through the leather. It would seem that a smaller needle may penetrate the leather easier, if it doesn't break, so I will try that next. And maybe even drop down to a 207 size thread. I appreciate you taking the time to respond to my post.

CFDBattChief

[Aven]

1 hour ago, CFDBattChief said:

Thank you for the reply, Handstitched. Yes, in mm, a sole bend is roughly 6.3 mm (1/4") thick, however it is the most stiff, dense, and hard leather that we use. It is mostly used I believe for making the soles of shoes, hence the name sole. We are making a little progress after having tried many different things. The dry leather actually seems to do better than if we try it while damp. I tried a spear point needle size of 28 using 277 bonded nylon thread, and even if I take it nice and slow, you can see the needle start to bow as it is forced through the leather. It would seem that a smaller needle may penetrate the leather easier, if it doesn't break, so I will try that next. And maybe even drop down to a 207 size thread. I appreciate you taking the time to respond to my post.

CFDBattChief

Yes, sole leather is the leather used for shoe sole.  It's really thick veg tan that's been seriously compressed.

All the machines I know if that can handle sole leather are beasts like the Landis McKay stitcher.

[RockyAussie]

I have a similar machine and have a fair bit of experience with stitching sole leather as well but not with this machine. Not that it could not I guess but here is the main point....Whenever I have done sole leather I soak it in warm water with a little detergent until it becomes softer and pliable and behaves more like a bridal leather feel.

This is sometimes left to soak for some hours and then put into a damp towel to mellow overnight. The needle should be a triangle shape tip or at least an LR shape but definitely not just a round point. You need the hole to allow the needle and thread to pass through easily. Lastly with regards to the thread breaking back off your bobbin until you can just see the loops showing on top and then re tighten a bit and back off the top tension a little. For some reason running a looser bottom can work and and stop the thread breaking. May not be smack in the middle but do you think that matters here?