chapelstone Report post Posted January 8, 2015 Like a lot of people on here, I am struggling with which machine to get. I have not been able to find a chart that correlates thread size with leather thickness. My question is; how light of thread and needle size do I need to sew two layers of 4 oz veg tan? How heavy of thread and needle do I need to sew two layers of 10oz? Some of the heavy machines say they will sew as light as 69 thread size. Is that realistic? I appreciate the time the experienced craftsmen spend answering rookie questions. Thanks in advance. Quote Share this post Link to post Share on other sites
silverbullet Report post Posted January 8, 2015 I'm no expert but I look at other items sewn and judge what to sew with. 69 seems to work well on wallets and thinner leather items . Now for heavier like holsters I choose to sew with at least a 207 , even that depends on the thickness too. If you want your stitches to show off your work or high lite the design pick the size and color you or your customer like. If you sew by hand the awl you use should be just big enough to press your needle thru but not with thin thread the holes look gigantic done that way. Well at least to me they do. Hope this might help nothing is in stone even doing leather . It's what you like some like rivets and sewn areas. Just keep having fun do the things that appeal to you and your customers. Gary, Silverbullet Quote Share this post Link to post Share on other sites
JLSleather Report post Posted January 8, 2015 (edited) Needle and thread size aren't really determined by leather thickness, so much as the intended use of the project. I've sewn 4 oz (2 layers 2 oz) with a 16 needle, 42 thread, at about 9 stitches per inch. 8 oz (2 x 2oz + 4oz) with 18 neeele, 69 thread 6-7 spi 8 oz (2x2ox + 4oz) same 22 needle 138 thread 6 spi 12 oz (8 oz + 4 oz veg) 22 needle 138 6 12 oz (8 +4 as above) 23 207 6 12 oz (8 + 4 as above) 24 277 6 I could go on, but you get the idea. Some of the selection of thread / needle size is just cosmetic - - different look. Your two layers of 4 oz could be stitched with 69 or with 346, and anywhere between, depending on what you want to do. And two layers of 10 oz is not so very much, and wouldn't require a "heavy" machine. It sounds like you need a "medium" range machine. As a rule with equipment, I like to cap the projects at about 60% of the machine capacity. If you need to sew 1/4" regularly, get a machine that will stitch 3/8" (without struggling). Personal opinion, i think the "heavy" machines you see around this site "could" do 6 oz leather with 138 thread. To get down lower than that would require considerations ... OH, and keep in mind that the distance from edges and the number of stitches per inch must be considered. Larger thread requires a larger needle, and a larger needle requires a longer stitch length to avoid weakening the leather with holes too close together. Edited January 8, 2015 by JLSleather Quote Share this post Link to post Share on other sites
TwinOaks Report post Posted January 8, 2015 OH, and keep in mind that the distance from edges and the number of stitches per inch must be considered. Larger thread requires a larger needle, and a larger needle requires a longer stitch length to avoid weakening the leather with holes too close together. Larger needles also need a little more room from the edge to prevent edge swelling at each stitch. I've personally ruined a few projects before figuring this out. Quote Share this post Link to post Share on other sites
Tramps Leatherworking Report post Posted January 8, 2015 Needle and thread size aren't really determined by leather thickness, so much as the intended use of the project. I've sewn I could go on, but you get the idea. Some of the selection of thread / needle size is just cosmetic - - different look. Your two layers of 4 oz could be stitched with 69 or with 346, and anywhere between, depending on what you want to do. And two layers of 10 oz is not so very much, and wouldn't require a "heavy" machine. I concur with the above, I think too often people get confused between "thread strength" and "cosmetics." #69 thread is actually pretty damn strong --- but, when you see people using 207+ for knife sheaths a lot of people assume that is for strength, when it is actually cosmetic... I was taught that when choosing a thread for strength, optimally, you would want the thread to break before the leather was destroyed... (Your experience and teaching may vary) Quote Share this post Link to post Share on other sites
ramrod Report post Posted January 8, 2015 Larger needles also need a little more room from the edge to prevent edge swelling at each stitch. I've personally ruined a few projects before figuring this out. good point. i've been down that road before. it takes only a few stitches to figure out that your edge is gonna be wavy. i've been able to minimize it with a mallet gently banging the edge. the customer didn't notice, but I knew it was there. Quote Share this post Link to post Share on other sites
JLSleather Report post Posted January 8, 2015 when you see people using 207+ for knife sheaths a lot of people assume that is for strength, when it is actually cosmetic... Yep. Not much strain on a knife sheath. I get a kick outta them boys talking about holsters needin' at least 277 thread, because [as the story goes] less than that could break if there was a "struggle for the weapon". To those who think that a holster can be pulled apart after sticking with contact cement and sewing with 207 thread -- SHOW me Quote Share this post Link to post Share on other sites
chapelstone Report post Posted January 10, 2015 Looks like with all the demand there is out there, someone could develop a heavy medium weight or a light heavy weight machine to accommodate that market. Am I understanding correctly that a medium weight machine will top out at about 207 thread and a heavy machine will bottom out at around #138. And that there is not a machine that is good on a range from 69 to 277? I am just new and trying to figure it out. And thanks for all the input. I appreciate this site because people are so generous with their experience and it is very helpful to others. Not many industries work that way. Quote Share this post Link to post Share on other sites
Tramps Leatherworking Report post Posted January 10, 2015 Looks like with all the demand there is out there, someone could develop a heavy medium weight or a light heavy weight machine to accommodate that market. Am I understanding correctly that a medium weight machine will top out at about 207 thread and a heavy machine will bottom out at around #138. And that there is not a machine that is good on a range from 69 to 277? I am just new and trying to figure it out. And thanks for all the input. I appreciate this site because people are so generous with their experience and it is very helpful to others. Not many industries work that way. This has baffled me for quite sometime also, we can land robots on mars, but we can't engineer a sewing machine to sew 69 through 415 thread? Quote Share this post Link to post Share on other sites
