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Thread Recommendation For Junker And Ruh Sd28

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I am looking for suggestions from anyone who has experience with a Junker and Ruh SD28 with regards to compatible thread. I have a machine due to arrive tomorrow and am trying to prepare for using it. I have emailed Henry but have not heard back yet (probably pretty busy with the Christmas season on us). I hope to use the machine for stitching uppers to midsole on the stitchout constructed shoes I am making. I am currently hand stitching using waxed nylon thread that measures .030" diameter. I would like to stick with either waxed nylon or waxed polyester since I can get it in various colors. Seems like linen/waxed linen thread comes in any color you want as long as it is black or white. I have read that nylon and polyester thread can be more abrasive than linen thus shortening the life of thread guides. However, this is just a one person hobby so I would think that wear would be minimal for my application. The manual specifies the use of flax fiber linen 6 strand right hand twist thread but I'm not sure if 6 strand from the early 1900's corresponds with what is currently termed 6 strand. Right hand twist throws a bit of a monkey wrench in this too as it appears that most nylon or poly twist thread that is available is either left hand or unspecified and thus, probably left hand to be compatible with modern machines. Maybe even "Tiger" thread is a consideration to avoid the right hand twist issue?

I also need advise on what needle size would be required for .030" diameter thread. The machine is coming with one size 6 needle. I have read about the scarcity and expense of needles for these machines but have been in contact with Henry on obtaining needles.

Thanks for any input.

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Is there any reason you didn't ask Henry to send a spool of the correct size and twist of thread?

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I haven't been able to reach him by email yet. I asked him similar questions as I've posted here and was checking on suitable needle size, availability, and cost as well. I just got a message that the email was undeliverable so I've just PM'd him. In the meantime I did some checking on the Crispin Colloquy forum for more information and gleaned a little bit. There were some folks there that talked about using waxed polyester as well as braided poly. But there really wasn't much discussion on that particular subject on that forum.

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Okay, I see your problem now.

Since neither of us know how the needle number correlates to the thread sizes, I'd wait for the machine to arrive, then try various sizes of waxed linen thread. You can buy them in skeins from various suppliers, including Hobby Lobby and Tandy.

My rough guess is that if the needle is a medium size, you'll want to use somewhere around a 6 or 7 cord linen thread. What I don't know is if it needs to be shoe machine right twist, or if the standard left (Z) twist is okay.

When the machine arrives, measure the diameter of the needle. Since the needle on the Junker punches the hole without an awl, it needs to be about 2x the diameter of the thread it uses (to account for the lockstitch knots). Thus, a 1.7mm diameter needle (at the eye end) can easily manage 1mm thread without difficulty. That equates to either #554 bonded, or 8 cord linen thread (.83mm D). This needle is double the diameter of the thread.

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Actually, I think that a curved needle would need to be at least 2mm diameter to withstand the shock of piercing sole leather without breaking on impact. It would still run 8 to 10 cord thread.

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OK, I've got some more details as the machine arrived today. First, thank you Wiz for the information you provided especially regarding size of needle relative to size of thread. Regarding the required strength of the needle, I actually will only be sewing the upper (up to 2 layers of 6 oz. chrome tan with relatively soft temper) to 8-9 oz veg tan midsole. The hair side of the midsole leather is sanded/roughened for good glue adhesion so even though it is hard temper, it is softened by the roughing. I don't sew the crepe subsole or the synthetic sole (usually a Vibram rubber sole). These components are just glued to the midsole.

So I checked the thread that came with the machine. The ancient spool is marked "6 cord" and the thread (presumably linen) measures .030" and is indeed right hand twist. I can't tell if it is waxed/lubricated or dry as I've never used linen thread before and it is very old. The #6 needle that came with the machine measures .075" at the eye which would agree with your rule of thumb for the needle to be approximately 2X diameter of thread. This will work perfect for the .030" diameter thread size that I have been using to hand stitch the uppers to midsole. Unfortunately it sounds like Henry only has size 5 needles so I may have to do more searching for some size 6 needles. I only have one needle at this time so I will be proceeding very cautiously in trying the machine out.

Now the question that remains is type of thread to use. Browsing thethreadexchange.com, polyester thread specifications list 6-cord (government) corresponds with size 415 (commercial) with a nominal diameter of .0283". However, I can't seem to find right hand twist in polyester or waxed polyester or nylon (also checked Maine Thread). Waxed linen is readily available in 6 cord right twist but only in white or black. I mostly use dark brown thread for the shoes I make. I suppose the white linen thread could be used but it does create a stark contrast with the dark brown leather I generally use. Tiger thread is available in .8mm (.031") and many colors including dark brown. Since it is a braided thread, right hand twist becomes irrelevant. It may be a good alternative although I don't know how the braided look will compare with the traditional twisted look. Will have to try it and see.

Finally, one of my concerns was whether anyone had been successful using waxed thread for the needle thread instead of using dry thread and running it through the lube pot. The Junker&Ruh manual actually describes using gum tragacanth rather than liquid wax in the lube pot for the dry needle thread. I would prefer to use waxed thread for the needle thread to avoid the use of the wax pot because it seems like liquid wax or gum trag will create a mess. The question is whether the waxed thread has enough lubricity to work for the upper thread. The Junker&Ruh manual specifies waxed thread (linen) for the bobbin thread.

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You should look up the Campbell-Randall website. They sell unwaxed, "glazed" Barbour's Irish linen thread, in various cord sizes and twists. I used to get their 5 and 6 cord, left twist, for use in my previous Union Lockstitch needle and awl machine. I used their Lax Wax concoction to lubricate the thread as I sewed. It dried inside the leather a few hours later. I think this thread and Lax Wax will work well for your shoes.

Who knows" They may even have a random curved needle in a drawer that fits your Junker Sd28.

Edited by Wizcrafts

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I actually have the Campbell-Randall website bookmarked as they are a great source for linen thread as you mentioned. Frankford Leather also stocks it. However, as I mentioned above, you can only get the linen thread in white or black. I use far more dark brown than any other color. I am curious to know your experience with the Lax Wax. I've been hoping to avoid having to use any lubricant, as I mentioned, just because it seems like it would be more messy and an additional hassle compared to just using modern pre-lubricated (waxed) thread. There is also still the issue of needing to run waxed thread in the bobbin as that is a stated requirement in the manual.

I wonder where the other users of Junker & Ruh machines are? I know I've seen the machines discussed on the forum before. I'm surprised no one has chimed in about experiences trying to use modern threads. They really are cool old machines.

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Curved needle machines belong in the domain of shoe repairs. That's why you don't see too many posts about them here. We are mostly straight needle machine users and at that, most are brand new to machine sewing. A few of us old timers may have used a curved needle machine in the past and a few still own working models, like your Junker. For me it was always straight needles.

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It is in Canada and wholesale only, however labelle supply has needles, wax, awls and thread for shoe machines. I wouldnt be surprised if they have needles in a drawer that would fit if cambell randall does not..

They have a good selection of right and left twist linen in 4-8 cord, They also haven regular poly in up to 8 cord, and braided poly in 6 cord. I believe braided poly is usable in right or left twist machines.

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I was seriously looking for a curved needle machine last year to do sole replacements. The expense of the machines and parts/needles made me back off for a while. Also, I was repairing work boots that had soles almost 3/4 inch thick. Not very many curved needle machines can penetrate that thickness.

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Thought I'd follow up with what I've learned so far with the machine. The ancient linen thread that came with the machine would break (upper thread) every time I tried to use it while trying to draw the lower thread up into the leather. While I waited for new thread to arrive I decided to completely clean the machine to remove all the sticky accumulation of gunk from all the years of previous use. Turns out gun cleaning solvents work great for cleaning away all the gunk (tested them on the underside of the base of the machine first). Then I loosened the bobbin tension slightly and tightened the upper tension some. I had decided to start off trying "Tiger" thread since the woven thread would eliminate the concern for finding right hand twist thread. The .8mm thread arrived and I spooled some up and gave it a try. I bypassed the lube pot since the Tiger thread comes pre-waxed. It worked perfectly on the first try. This little Junker & Ruh SD28 machine is really cool. The stitching is virtually indistinguishable from the way I hand stitched before. In less time than it used to take me to mark the upper to midsole with an overstitch wheel and punch the holes with an awl, I was done stitching with the SD28. I would have spent another 30-45 minutes hand-stitching the seam.

I imagine there are other alternatives to the Tiger thread that would work (certainly linen but it's hard to find in various colors) but I'm thoroughly satisfied with the Tiger thread. This is the first time I've tried it and I'm really sold on it.

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Do you think 1mm. Tiger thread would work with a larger needle, say 7-8?

I'm doing the exact same as you used to do at the moment: stitchdown construction shoes with 5-6oz. uppers folded out over a 9oz. sole bend midsole. It's taking me freaking ages to do the hand sewing, and I've been looking into getting hold of an old Junker & Ruh SD28 or Pedersen #308. Like you, I only make a few pairs a month, so it won't see too much heavy use.

One thing I wonder, is if the machine would be able to stitch through an additional 3mm. rubber outsole. I do my shoes Viberg style, where the first line of stitchdown only goes through the upper and midsole, and the outer row of stitchdown goes through the upper, midsole and Dainite rubber outsole. The outer row is what takes the most time, since I can't use a sewing awl inside the waists of the shoes and have to saddle stitch the last 20 stitches with curved needles. That alone takes like 40 minutes per shoe. It would be amazing if the Junker would be able to handle that job. Thoughts?

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I have now successfully used both .8mm and 1mm Tiger thread. I used a size 5 needle with the .8mm and tried both a size 6 and size 7 with the 1mm. I prefer the look of the 1mm to the .8mm for outstitching shoes and I'm now using that exclusively. The size 6 needle worked fine with the 1mm thread. If I was using a particularly dense leather or for some other reason having trouble getting the knot to draw up into the stitch then I would switch to the size 7 needle for the slightly larger hole. There is not a lot of difference in the size of the 5-7 needles. Initially the hole seems quite large for the thread but as you press the edge down for gluing the sole to the midsole the stitching fills in nicely.

Don't know about stitching through an additional layer of rubber outsole as I haven't tried that. You may have to go to a larger needle to do that. As far as the force required to do it I can only say that stitching through 2 layers of 5-6 oz leather (heels counter + upper) and 9 oz of hard temper midsole is effortless. It has lots of mechanical advantage.

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That's great news! Your thread on this matter and all the posts here couldn't have come at a better time.

And so begins the search for a machine in working order... Thankfully they aren't that rare here in Europe, but people have started charging upwards of $500 for them on Ebay. When they do pop up locally, they usually sell for a couple hundred.

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