Union Special 51900 Alternate Presser Foot?

[Ogoki]

Hello all,

I have been doing some work lately on a Union Special 51900BH.  This would have been a triple needle chainstitch machine, but it is operating on one needle only for its current purpose.  I have been getting a lot of skipped stitches on the lighter materials.  I am pretty sure this is due to the gaping hole in the presser foot around the needle, which allows the sleazier materials to lift with the needle.

Does anybody know which presser feet will interchange with this machine?  Below is a picture of the one that is currently on there.

I see one on ebay (#52820) that looks like it might work, but I would rather not gamble, if somebody knows the answer... http://www.ebay.com/itm/1-new-5280-16-presser-foot-for-UNION-SPECIAL-52800-52900-sewing-machines-/291692870613?epid=1971259328&hash=item43ea3ffbd5:g:TcIAAOSwDuJWzfDX

Going by the parts book, it also looks like a #6520 might work, but again, I am guessing.

Are there any Union Special experts out there?

Thanks for any help.

Edited August 26, 2017 by Ogoki

[gottaknow]

Greetings. I work on Union Special chainstitches every day. I'll check those part numbers for you and can help with trouble shooting. 

Regards, Eric 

[gottaknow]

Ok, that ebay presser foot #52820 is for a Union Special 51900BZ, which is a chainstitch machine with an optional top cover hook. It's used for sewing pocketing on jeans. I have two of them. The correct part # for your machine is either 51905 A-7 for 6 and 7 gauge or 51905 B-9 for 8 and 9 gauge. You can tell the gauge by the part number on the throat plate. It will be stamped either at the beginning or end of the plate part number with the gauge size. Those two feet may be obsolete.

By looking at your picture closer, someone removed a bunch of the foot material which will definitely give you looper skips due to the foot not holding the fabric secure so a loop can be formed on needle bar rise. There is no cure with the exception of a new foot. With thicker material, it has a better chance of not skipping.

There's a good chance I have a foot around that will work. I just need to know the needle gauge as I mentioned above. Let me know if you like.

Regards, Eric

[Ogoki]

Hi Eric,

Thanks for the response!  I will check the number on the throat plate next time I'm there.  Right now I am using a size 20 needle, if that helps you any.  Are those part numbers meant for this machine in its stock, 3-needle operation?  Or are they single-needle variants?

Also, is it really not possible to adjust the stitch length on this machine?  I have been told it isn't, and I don't see any obvious way to do so...

Thanks again.

Kevin

 

[gottaknow]

Those part numbers I mentioned were for the machine as it came from the factory. In your case, a 3 needle chainstitch flat felling machines. There are no less than 20 machines of this same casting. Union Special never intended a machine to be modified, so there's no part numbers for variations, except for gauge size. It's true a lot of the parts can interchange, including the presser foot. The foot you saw on eBay isn't for any of the sub-classes. If the needle slot is centered for your needle, then great. Most chaining feet have a small groove for proper thread chaining.  Also, you should be able to change the stitch length. I'll try and attach a PDF with how to do it. All these subclasses use either class 128 or 108 needles available in many point types and size. 

Regards, Eric 

[Ogoki]

OK, so I guess my best bet is to find the original 3-needle foot.  I just found the Union Special parts manuals and it seems that the part numbers are 35820 P-8 and P-9, if that makes sense.

Those stitch-length instructions would be great, if you have them.  The stitch length on this particular machine is rather long and it looks kind of ugly...  The Union Special site just seems to have parts manuals, which do have basic oiling and threading instructions, but that seems to be it.

Thanks again.

[gottaknow]

Here is a PDF to show you how to change the stitch length. I haven't had a chance to look for a foot yet.

Regards, Eric

US51900BH.pdf

[Ogoki]

Much appreciated!!!

[Ogoki]

I set the machine to a stitch length that looks much nicer, but it started skipping stitches like crazy.  So, I backed it off and seem to have found a sweet spot where it skips very rarely, but is still too long for my liking.

Any ideas as to why it wouldn't loop properly with a shorter stitch length?  Does tension generally need to be adjusted with stitch length on one of these?  Or does that sound like it needs a needle/looper/timing adjustment?  If so, is there a proper manual for these things with an "Instructions for machinists and adjusters" section?  I am happy to improvise with my own machines at home, but not so much at this job...

[gottaknow]

Setting a chainstitch properly is nothing like setting a lockstitch. There is an entire different set of parameters, terminology, and troubleshooting requiring a different skill set. There are manuals still available from Union Special's website, however without a basic understanding of how a chainstitch works, you will likely struggle. Before you do anything, I'd get a different foot to eliminate the flagging issue. After that, I can give you an outline of how to proceed. There are some general guidelines that are common to all chainstitch machines. One thing's for sure it will never be the fault of the bobbin case.

Regards, Eric

[Ogoki]

From what I can see on the Union Special site, there is only a parts manual for this series.  My experience with chainstitchers is limited to my Champion 77 and an old Puritan triple stitcher, both of which are single thread machines (if I recall the Puritan correctly), and different from these two-thread machines.  In any case, I am confident that with a manual and/or a bit of guidance, I can wrap my mind around this.   The "flagging" issue seems to be virtually non-existant when stitching a few layers of 15oz. denim (at the risk of getting the boot I must admit that this isn't being used for leatherwork), so I feel that I could ignore that variable with the right troubleshooting material, i.e. three flat layers of 15oz. denim.  The flagging occurs with thin materials, and it also skips when going over the seams, where I might have more like 12 layers of denim (I do use a height compensation tool to pin down the fabric by the needle, and walk the machine over the seams very slowly).  And, of course, when reducing the stitch length the machine becomes basically useless, which is the problem I would really like to solve.

Is there a proper service manual for any similar machine that might help me?  I also recently picked up a baby lock serger, which is a serger and a chainstitcher.  It doesn't loop properly either, so I think it is time to learn about chainstitching machines....

[gottaknow]

The specs you have to know are looper gauge, looper avoid, looper travel, and synchronization. Each Union Special machine in this general chainstitch class ( of which there are several hundred variations) , have specific values. Some do overlap for sure. I have a lot of US manuals, so I'll wade through them and see what turns up. If you know what the looper gauge and travel is, you at least have a starting point. The other issue is these machines are capable of being set with two needle classes. 128 and 108. The 108's are shorter. It's likely class 128 which requires a different looper avoid setting than  the 108's. So I guess I need to know which needles you're using first off.

Also, here's some general information. It covers the style of looper in your machine "across the line of feed loopers", it's pretty close to the beginning.

Regards, Eric

Loopers and hooks.pdf

Edited September 13, 2017 by gottaknow
attach

[Ogoki]

Thanks again!  I'll have a look through that pdf and see what I can find out about the looper.