Tejas

I think I recall from posts on another forum that Juki bought Nakajima and that the Nakajima 280 L is the same as or similar to the Juki DNU 241. I also think that I recall Juki no longer stocks all of the parts. A user manual is attached. Juki-241H-Nakajima-280L.pdf

A zig zag machine might be walking foot, but not compound walking-foot -- lacks needle-feed.. Depending on your application, a compound walking-foot can make a difference. I think that a compound walking-foot machine would be beneficial for your application -- sewing bags and camping stuff out of canvas, cordura, nylon and leather -- and that zig-zag is not necessary or even very useful. I have both and use the zig zag machine only for sail repair. Apologies if you already know the following. A compound walking-foot machine has both drop-feed (bottom-feed) and needle-feed with an alternating presser-foot (walking-foot). Drop-feed is accomplished by a set of serrated feed-dogs that grip the material between the feed-dog and the presser-foot. When the needle is lifted out of the fabric, the feed-dog raises out of slots in the base of the machine, and grips moves the material. At the end of the movement, the feed-dogs drop and relinquish the grip. Needle-feed is accomplished by moving the material with the needle when the needle is in the material as the needle follows essentially an elliptical path. Needle-feed also mitigates the tendency of lower layers of material to feed faster than upper layers with drop-feed machines. The following links might be helpful. The YouTube video also shows the control possible with a servo motor, and do click on "show more." http://en.wikipedia....Feed_mechanisms As for a Sailrite clone, you might want be interested in the following links: https://sailrite.wordpress.com/2013/06/13/the-history-of-the-sailrite-ultrafeed-sewing-machines/

Here is a link to a very good quality pdf of the Juki 563 manual. http://keysew.com/Webpages/DemoImages/Juki_LU-563_Instruction_Keyfooter.pdf

Here's a Juki 1541S with a servo motor for $1610 from keysew. Gregg at keysew is a frequent poster here. I bought my machine from him. http://store.keysew.com/sewing-machines/juki-sewing/juki-dnu-1541s-with-assembled-power-stand-setup-ready-to-sew

Buying a used machine, especially from an individual, can be challenging. I've looked at many machines and bought four different used machines from individuals, and all had later discovered surprises such as missing parts or gummy lubrication that interfered with operation. This is what I have done. I'm quite interested in what other folks recommend. Try to find a manual online, or at least a few pictures. Sometimes machines are not even complete. Take scissors, small screw drivers, thread and sample material(s), needles and of course the manual. Using different colored thread for needle thread and bobbin thread helps to be able to see the stitches and tension. Ask the seller to demonstrate the machine if they can -- sometimes the seller is selling for someone else. Look top, bottom and underneath at overall condition and especially for rust. The condition of slots in screws can indicate heavy-handed maintenance. The electrical connections on older machines can also be a problem. Test all the functions you are interested in. Wind a bobbin with your thread and using your top thread, sew your sample material(s). Verify that the stitches look OK top and bottom. To test stitch length, set the stitch length, un-thread the needle and with the hand-wheel operate the machine sewing forward, “sewing” a piece of light cardboard or heavy paper for a few inches. Then with the hand-wheel operate the machine in reverse. The needle holes in reverse should perfectly match the holes going forward. Remove the cardboard and measure the actual stitch-length versus the setting. Do that for the start and end range of the range(s) you are interested in.

A pdf copy of the LU-1500N Engineer's Manual that has a bit more detail on lubrication is attached. Would you please attach a copy of the manual you used. LU-1500N Engineer's Manual.pdf

I don't know. Double-wrapping is a technique used when the tension discs are maxed-out. That is not your case. I just thought that a double-wrap might result in enough tension to make a stitch were the tension discs released when sewing over thicker material.

Assuming that TinkerTailor has identified the problem, and your machine might be just on the edge of forming stitches when the tension discs are released, I'm wondering were you to double-wrap the thread around the tension discs, would that provide just enough thread tension to avoid skipping stitches. Double-wrapping the thread is a technique used by DIY boat canvas sewers sewing with home sewing machines.

Oops, I failed to complete "attach this file." After Add reply, I'll check. sewing_troubleshooting_chart.pdf

Attached is a comprehensive Sewing Machine Troubleshooting Chart that lists 31 causes and solutions for skipped stitches. TinkerTailor's cause is not explicitly listed, but cause 11 and 12 is close. I've seen his cause explicitly discussed on a UK vintage sewing machine forum.

Access please.

You might want to try a more general sewing machine forum. Here is a link to sewing machine forums with good coverage of home sewing machines. http://www.thesewingforum.co.uk/index.php

I've used a Consew 206 RB5 for boat canvas, and it could handle the layering described in my earlier comment with V-92 thread. I believe the RB5 is made in China. I think I actually preferred the circa 1950s Singer 111W155, even though it had no reverse and setting the stitch-length was a bit of a hassle.

Sewing canvas with only two or three layers can be difficult. For example, simply sewing a double-fold hem over a semi-flat felled seam is nine layers. Sewing over a flat felled seam would be 12 layers. Doulble-hems at a corner also result in nine-layers but can be mitigated to fewer layers by mitering the corner. Add some webbing, and layers and thickness can increase quickly. However, a Singer 111W155 I had could easily handle most situations with V-92 thread.

Assuming you mean how to search for something on the forum, try using google with the site: parameter. search-term [search-term] site:leatherworker.net

You might want to ask that question on http://www.upholster.com/upholstery-forum/ There are marine canvas sewers on the forum who have commented on PTFE thread. PTFE thread seems really slick, so I'm guessing wear is not a problem, especially in low volume production use.

As I had said, Tenara is much more expensive than bonded polyester. However, Sunbrella is guaranteed for ten-years. Within ten-years almost anywhere here in the South, bonded polyester will weaken, and the seams even come undone from UV. Pay now, or pay later.

Tenara and other PTFE thread is a monofiliment and essentially impervious to UV. I use it on boat canvas here in Texas and ten-year old stitching shows no UV deterioration and will probably outlast Sunbrella fabric. Here are a few quotes from Gore. "Unaffected by Sunlight" "GORE® TENARA® Sewing Thread maintains its strength even after regular exposure to UV sunlight. UV resistance is built into the thread, and is not a coating or additive that can wear off." "Weather-Proof" "GORE® TENARA® Sewing Thread remains flexible and strong in extremes of hot and cold. It won’t absorb water and it resists acid rain, salt water, pollution, snow and freezing." Tenara comes in a few colors and also clear, and is available in V-69, V-92, V-138 and V-207, but is much more expensive than bonded polyester. In discussions on another forum, some canvas sewers claim the SolarFix PTFE thread is easier to sew than Tenara. I've only sewed V-92 Tenara and use Singer MR4 135x17 needles.

I don't recall were this tip comes from, but a different forum I think. To test stitch length, set the stitch length, un-tread the needle and with the hand-wheel operate the machine sewing forward “sewing” a piece of light cardboard or heavy paper for a few inches. Then with the hand-wheel operate the machine in reverse. The needle holes in reverse should perfectly match the holes going forward. Remove the cardboard and measure the actual stitch-length versus the setting. Do that for various stitch lengths.

Not graphs but possible with a spreadsheet, I made a spreadsheet of selected cylinder head machines. Attach Files does not allow spreadsheet upload. Attached instead is a pdf version of the spreadsheet. The data is incomplete and might not be correct. If anyone would like to expand the spreadsheet to more machines, I can send the file via email. Cylinder Head.pdf

Excellent video!

Quote from source referenced below: Penetrating Oil Test In a thread in the antique machinery forum, there was a discussion what to use to free up a part. Southbendmodel34 had mentioned a study in Machinist Workshop stating that Automatic transmission fluid and Acetone mixed was the best. I just received a newsletter today from Tim Carter mentioning the same study. He had included the results of the test, which I thought interesting. A study done by Machinist's Workshop magazine in their April 2007 issue looked at different penetrating oils to see which one did the best job of removing a rusted bolt by measuring the pounds of torque required to loosen the bolt once treated. If the study was scientifically accurate, it turns out a home brew works best! Here's the summary of the test results: Penetrating oil ..... Average load None ...................... 516 pounds WD-40 ................... 238 pounds PB Blaster .............. 214 pounds Liquid Wrench ...... 127 pounds Kano Kroil ............. 106 pounds ATF-Acetone mix....53 pounds Source: http://www.practicalmachinist.com/vb/general/ot-penetrating-oil-196347/

Here is link to very readable copy of the users' manual. http://keysew.com/Webpages/DemoImages/Juki_LU-563_Instruction_Keyfooter.pdf

Just in case you are not aware, Sailrite Ultrafeed sewing machines are walking-foot machines but not compound walking-foot machines.

Not precisely on-topic, but here is a link to a service manual for the singer 66, 99, 15K and 201. Since the manual was created by a non-profit, I made a contribution. http://www.tfsr.org/publications/technical_information/sewing_machine_manual/