Needle Size, Thread, Spi And Leather Weight Rule Of Thumb?

[Babbs]

thanks Wiz, appreciate all the help you give us all !

[Procyon650]

I agree, Wiz thanks for all the information. I would have no idea what I was doing with my Techsew 2700 without this forum and your posts.

[msdeluca]

Great info Wiz. Thanks for sharing your knowledge.

[geiercustomleather]

On 3/2/2014 at 3:38 PM, Wizcrafts said:

I try to match the size and breaking strength of the thread to the project. Plus, one has to choose a combination that conceals the lockstitch knots between the layers. So, here are some of my general recommendations for you.

• For very thin and/or soft projects, 3 - 5 ounces: #69 thread with a #18 needle (below 441 practical limit. Round point only.) (8 /inch)
• For thin projects, 6 - 8 ounces: #92 thread with a #19 or #20 needle (at practical bottom 441 limit. Round point only.) (7 /inch)
• For 9 - 12 ounces: #138 thread with a #23 needle (typical, consistent 441 bottom limit. Smallest leather point 794 needle) (6 /inch)
• For 13 - 20 ounces: #207 thread with a #24 needle (great for stitched belts, single and double leather) (5.5 /inch)
• For 21 - 28 ounces: #277 thread with a #25 needle (5 /inch)
• For 1/2" to 3/4": #346 thread with a #26 needle (4 /inch)
• Extra heavily stressed projects, 3/4" to 7/8": #415 thread, with a #27 needle. (3.5 to 4 /inch)

Exceptions

• Holsters, outside the pants, with security thumb-breaks: If at least 1/4 inch thick, use #277 thread, at 5 /inch. The knots can be buried inside the layers and the 44 pound thread breaking strength resists tearing during a struggle for the gun.
• Sam Browne duty belts, 1/4" to 5/16" should be sewn with #277 thread, at 5 /inch.
• Extra thick, double leather (over 3/8") professional weight lifter's belts should be double row stitched with #346 thread, at about 3.5 or 4 to the inch. These belts take a tremendous amount of stretching and abuse.

Stitches per inch

I use long enough stitches to look good on top without forming loops on the top or bottom when the project is bent (like a belt). Conversely, when the work calls for closer stitches, you have to make sure they don't perforate the stitch line.

Why?

"S" point needles, like the type 974 Schmetz makes for 441 clones, slice the leather with inline, wedge shaped cuts. This buries the ends of the thread inside the top grain and makes it appear like the stitches are closer together. If properly spaced, thick thread adds to the strength of the package. But, if placed too close, the holes in the leather weaken the package beyond the thread's ability to secure it. In fact, if the holes are so close that the thread is stronger than the leather between the holes, it can slice right through them. Also, the larger the diameter of the thread, the bigger the knots formed by the lockstitches.

When sewing with thick thread, like 207 and larger, space your stitches out to avoid slicing through the leather: e.g., no smaller than 6 to the inch. When sewing with #138 thread & 23 needle, you can go a little shorter, to 7/inch. If you use #69 or 92 thread, 8 to the inch is okay.

Thread breaking strength list

1. #69 (T70): 11 pounds
2. #92 (T90): ~16 pounds
3. #138 (T135): 22 pounds
4. #207 (T210): 32 pounds
5. #277 (T270): 45 pounds
6. #346 (T350): 53 pounds
7. #415 (T400): 72 pounds

Off topic a bit.

I'm looking at a CB3200 as it can handle most of the things I currently hand sew but not sure if it can sew thread #69 and 3 oz leather (wallet inserts) as the specs seem to be all over the place depending on who's website you go to. Can the CB sew 3 oz leather (two layers of 1.5 oz)? I'm not making stuff at a full time rate but other on the side here and there so trying to narrow down the search for a machine.

Thanks, Billy 

[Wizcrafts]

3 hours ago, geiercustomleather said:

Off topic a bit.

I'm looking at a CB3200 as it can handle most of the things I currently hand sew but not sure if it can sew thread #69 and 3 oz leather (wallet inserts) as the specs seem to be all over the place depending on who's website you go to. Can the CB sew 3 oz leather (two layers of 1.5 oz)? I'm not making stuff at a full time rate but other on the side here and there so trying to narrow down the search for a machine.

Thanks, Billy 

I sincerely doubt it. You will need a lighter duty machine fir such thin leather and thread. Standard walking foot and tailoring machines can sew wallet interiors with #69 thread using a #18 needle. I don't know if you can even get #18 needles for the 441 clones. The smallest I found was a #19, which punches a hole that's just suitable for #92 thread.

All of the spring tensions on the CB3200, 3500, 4500 and 5500 are extra heavy. These machines are built with heavy thread and big needles in mind. The machine would have to be dumbed down to sew thin leather with thin thread and tiny diameter, easily deflected long needles.

[brmax]

Thank you Wizcrafts, as I had been curious lately and wondered if the 3200 may have different and or lighter tension and presser spring. 

 

Good day

Floyd

[BDAZ]

I have a 3200 which I love but use Singer Heavy Duty for thin leathers :

I have used on up to 5-6 oz leather.

Bob

Edited May 3, 2018 by BDAZ

[garypl]

2 hours ago, BDAZ said:

I have a 3200 which I love but use Singer Heavy Duty for thin leathers :

I have used on up to 5-6 oz leather.

Bob

Bob, does this Singer sew slowly or only at full speed?  For small, thin projects I am looking for a machine that runs very slowly.

Gary

[BDAZ]

It will never be as slow as a 3200. I have mine set up to stitch as slow as one  stitch every 4 seconds, but there is an inexpensive walking foot and leather needles available and I think it will give you good results on thin leather.The price is <$99.

Bob

[geiercustomleather]

On 5/3/2018 at 7:04 PM, BDAZ said:

I have a 3200 which I love but use Singer Heavy Duty for thin leathers :

I have used on up to 5-6 oz leather.

Bob

Thanks Bob!

 

[geiercustomleather]

On 5/3/2018 at 4:59 PM, Wizcrafts said:

I sincerely doubt it. You will need a lighter duty machine fir such thin leather and thread. Standard walking foot and tailoring machines can sew wallet interiors with #69 thread using a #18 needle. I don't know if you can even get #18 needles for the 441 clones. The smallest I found was a #19, which punches a hole that's just suitable for #92 thread.

All of the spring tensions on the CB3200, 3500, 4500 and 5500 are extra heavy. These machines are built with heavy thread and big needles in mind. The machine would have to be dumbed down to sew thin leather with thin thread and tiny diameter, easily deflected long needles.

Thanks Wiz! I'm still looking at one of these for sewing 6oz plus projects and will look at a smaller unit for the wallet interiors.