Domanoff ropewalk PL4-4 modification

[modeller_masa]

 

Hello,

I received Domanoff rope making machine PL4-4 yesterday. It was busy day to learn new machine and run some tests.

 

Unfortunately, the package was shocked during shipment, so I had to fix it before use.

 

 

 

The biggest gear (red) was removed, so it interfered with motor unit (green). 

 

 

Fortunately, the gear wasn't damaged, so I just pushed and fixed it like this. 

 

 

It doesn't touch the motor unit.

 

 

In addition, you may need to adjust the motor position using bolt. (red box)

 

 

The sample thread Domanoff might made is super better than my first job. I felt that this machine is 10 times difficult than Domanoff serving rope machine SM4.

 

 

Here is small tip. You can replace the ④ middle size bobbin (green box) to common wood bobbins. The size must be smaller than 55mm long and 35mm diameter. This machine can be adjusted traverse area in case of different bobbins.

 

 

This machine is extremely noisy machine. This is the loudest noise at 0 distance. It is 100 times louder than serving rope machine, and slightly quiter than 10 inch table saw. 

 

 

However, I need more noise and speed. The reason I need faster speed (① Drive: 4~5) is that winding speed of ④ bobbin is too fast. I can control the bobbin speed with ② Takeup knob, but it is not stable when it goes under +1 speed. Even +1 speed is so fast that I can't make tight rope than stock thread.

 

 

When I slow down the bobbin speed to 0.5 or 0.75, the motor becomes unstable, and eventually stops. The bobbin speed is a key to control tension, so when it stops, supply thread cut within a second. Only way I can run it with +1.0 bobbin speed is driving faster than +4.0 which causes 100 dB monstorous noise.

 

 

 

It's hacking time! I decided to remove the bobbin control system and make more reliable system at lower speed.

 

 

I used most parts of modification from spare parts, so I was able to minimize expense. The main motor to rotate bobbin is 775 motor with PWM controller. It was so fast and difficult to control at slow speed...

 

I bought $1 bowls, and used the sealing cap as pulley. 🙂

 

 

The smaller pulley is bobbin. 😆 The ratio is about 11:1.

 

 

I used two pulley and succeed to slow down the fast 775 motor 1/120 times. It is ideal speed I planned. (The picture's speed is 10% power input.)

 

I need longer M6 bolts to complete the bobbin motor modification and it will be the next week.

 

https://shipworkshop.com/products/other-tools/61-rope-making-machine

 

Did Alexey Domanoff know the issue? I think so. His new prototype machine uses stepping motor what I considered at the very beginning stage. It looks like his new machine is significantly better than PL4-4, and it can be quiter than before because of accurate bobbin winding speed. Only regretful thing is that it still uses jam-friendly bobbin holding mechanism. I would say that it must be replaced to quicker and easier clamp mechanism.

 

My next modification will be replacing the bobbin holding mechanism and minimizing noise. I'll upgrade my PL4-4 to new 6+1 machine by myself. 😆

[modeller_masa]

 

I designed new frame to install the new bobbin winding system. It needs more space. Also, I added space for soundproof shelter

 

 

It is all I can do for now. I need some bolts to finish the mod.

[modeller_masa]

 

I finished to modify PL4-4.

 

I reused most parts from stock and spares, so it didn't cost a lot.

 

 

I can control all the system with one hand.  

 

 

Some parts like this long screw thread were hard to get, so I connected two common bolts.

 

 

To use the bolts, I cut the bolt head with Proxxon table saw and HSS metal blade. It was extremely difficult and dangerous. It scattered sparks all over the places and it literally melted down. 😨

 

 

In addition, I changed the problematic stock bobbin holding mechanism to my new idea.

 

 

 

I made wood bolts and R-clips with fun. 😉

 

 

The stock metal bolts had many issues.

 

(1) 11.5 times heavy weight

(2) screw thread causes jam frequently.

(3) It takes long time to load and release bobbins. (About 30 seconds.)

(4) A bit difficult.

 

New wood bolt with R-clip solved all the problems.

 

(1) Reduced weight stress

(2) Much less jam

(3) 5 seconds quick release and lock.

(4) Super easy.

(5) Cheap.

 

 

I ran a test with cheap cotton thread. I added long middle area to check working thread easier and to prepare additional tension control system in the future.

 

 

This is a desirable condition according to a manual...

 

 

If a left drive rotates too fast or right bobbin stops to wind, the thread will cut within seconds.

 

 

In this case, a left drive rorates too slow or a right bobbin runs too fast. It is making useless loose rope.

 

 

Thanks to a slow bobbin speed mod, I can run a left drive 10 times slower than before which means I can run ropewalk at night without fear. Also, I can set and record bobbin winding speed from 8 to 100 which is clearer than previous analog knob. I'll replace the left drive motor to digital system like the bobbin.

 

I finally satisfy with my new gadget and can be sure that it will produce any kind of rope. It's time to go back...... What was I making? 🤔

[modeller_masa]

 

While I was investigating malfuntioning, I found that I missed key factor to run ropewalk. Tension must be tight to get a firm result. I planned to add tension control system to the right direction only, but it had to be bidirectional strong tensions...

 

 

At first, I tried to reinforce the wood bolt R-clip with washer, but it didn't help because the bobbins need delicate tension control. They should have not tight and not loose tension.

 

 

Probably the best tension control device is this. However, I can't add it to Domanoffs' because it needs extra space. Domanoff's bolts save spaces and relatively simple.

 

I decided to use another bolts to get tension for now and postponed additional (huge) modification till next months.

 

 

Looks like I finally read Domanoff's manual correctly. I'm running it at 0.5 Drive speed which is very slow and quiet. (The threads are Amann Serafil 300(200/2), 10 Tex, poly 100%.)

[wefalck]

Weren't the bolts for the feed bobbins meant to adjust the tension of the individual threads ? Uniform tension on all the threads is important for a smooth rope.

[modeller_masa]

7 minutes ago, wefalck said:

Uniform tension on all the threads is important for a smooth rope.

 

 

 

You got a point. It was my next trouble immediately encountered, and it almost drove me to despair. It is very difficult to maintain same tension with the bolt tension system. Here are some tips I found.

 

(1) Tighten all the bolts as much as possible. (Just below the cutting level) It usually works well with strong threads such as serafil polyester thread.

(2) Do a massage after rope making is done. The massage means twist and untwist all the wire slightly. It spreads the 'waves' evenly. Domanoff's system is only half meter size while conventional ropewalk requires several meters of railway, so the finished rope may needs to be massaged separately while the other ropes made by different ropewalks may be massaged simultaneously.

 

I'm still fighting with the issue. It is a bit frustrating - especially the massage takes too much time. I started to make pretty good ropes, but want to make them more flawlessly. I'll upload a post when I find better way or modify the feed bobbins to get even tension.

[wefalck]

Don’t know why the manufacturer used these bulky thumbscrews. The parts are commercial hardware, perhaps for that. The bobbin will run on the screw thread which will not allow a smooth running. I would use a bolt with just a short thread on it. There should be a spring washer between the frame and the bobbin. Just pulling together the frame will not allow precision control, but jam the bobbin. The tightening nut either has to have a nylon insert, or there has to be a locking nut to not work lose.

[Bob Cleek]

11 hours ago, wefalck said:

There should be a spring washer between the frame and the bobbin. Just pulling together the frame will not allow precision control, but jam the bobbin. The tightening nut either has to have a nylon insert, or there has to be a locking nut to not work lose.

The supply bobbins have felt washers on either side of them, inside the mounting forks (frames) through which the threaded bolt runs. The plastic material of the bobbin forks is "springy." Slight pressure on the sides of the mounting forks achieved by tightening the bobbin axle knobs is sufficient to compress the forks slightly and cause the felt pads to create sufficient friction against the bobbin to keep the thread tight as it is pulled from the supply bobbin. The nuts in the bobbin axle knobs have some sort of plastic on the threads which prevents their slipping when threaded. This permits the omission of a second bolt that tightens against the first to keep it in place on the threaded rod.

 

I'm far from any sort of expert on this machine. I've only had time to play with mine a bit and it's a slightly earlier design with a separate control box and a bit different planetary gear plate arrangement. I had problems in the beginning which were attributable solely to my own inability to understand the set-up instructions. I emailed Alexey and he was most helpful. The solution for my problem was in the instructions all along. (The control box isn't just three independent rheostats that control the speeds. It's "smart" with solid state control circuits that have to be programmed by the sequential pushing of buttons which isn't "intuitive." You've got to read the instructions and I hadn't gotten them right.

 

I don't have any issues with the noise on my machine.  If the noise increases as the speed increases, it's probably a vibration problem, no?

 

I can only suggest the following possible areas to troubleshoot. Failing that, I'd strongly urge you to email Alexey and ask for help before "re-engineering" the device. It's cleverly thought out and doesn't seem to take well to being modified, as you may have noticed when you substituted the wooden bobbin axles which defeated the friction mechanism on the bobbins which maintains the thread tension at that end.

 

1.     Check to see that the large gear (the "sun" gear in the planetary mechanism) is not mounted backwards on its axle. Yours is different than mine, but I mistakenly mounted mine backwards when assembling it and, discovering my error, had to correct that. The reversal of this gear may affect the gear alignment with the motor. (My machine's motor is a rubber "tire" friction drive against the edge of the large gear, unlike yours, which is gear driven.)

 

2.     When laying up three part rope, the fourth bobbin must be mounted on the machine in order to maintain the balance of the spinning planetary mechanism. 

 

3.     Bobbin tension is adjusted by tightening and loosening the bobbin axle knobs to pinch the felt pads against the bobbin sides. "Whorls" in the laid up rope occur when the tension on the bobbins is uneven and the thread feed slips or jerks. Even tension when loading of the bobbins in important.

 

4.     When laying up four part rope, a center core (a fifth strand) of smaller diameter than the other four must be run through the middle of the four laid up strands if the resulting rope is to lay up concentrically. If the core is omitted, the four strands will not lay up equally and the rope will be "lumpy."

 

5.     The tightness of the lay can be adjusted by moving the "windpoint" created by the crossbar fairlead(s) on the threaded posts projecting from the main ("sun") gear. See Alexey's post with his instructions regarding this at 

 

6.    The twist direction of the thread, left ("S" twist) or right ("Z" twist,) is important. If you are laying up right twist thread into rope, you must start with left twist thread. If you are laying up left twist rope, you must start with right twist thread. If your thread is twisted in the wrong direction (the twist varies, but most sewing thread is right twist,) you have to twist it back in the direction you want before loading it on the bobbins for laying up.

 

I hope these thoughts are of some help. As I said, if all else fails, email Alexey!  He's a great help.

 

Thanks for sharing your struggles here. I'm watching closely and learning a lot. I haven't had a lot of time to spend playing with my machine as yet.

Edited March 12, 2021 by Bob Cleek

[wefalck]

Only after my last comment, shortly before going to bed, I noticed that there were felt-washers between the bobbins and the frames.

 

While such a machine is an interesting engineering design challenge, I think there are too many degrees of freedom to make it really practical - unless you go into industrial production. Many of these variables have to be re-adjusted for each type of thread. For a three-strand rope I count at least eight: for each bobbin the friction and the tightness of wrapping the thread, the rope tensioning device and the winding speed that has to be adjusted as that bobbin fills up. All these have to be re-adjusted each time you start a new cycle.

 

Personally, I would think carefully about the maximum length of rope I need and arrange a batch-type rope-walk for that length. With a proper set-up, there are only two variables to control: the overall tension of the threads, if set-up continuously, and the number of twists for the threads. The tension you can control with a weight and you take note of the weight you used for a good rope. The number of twists you can count and record. Therefore, the settings are quite reproducible, something that I would find difficult to achieve for these continuous rope-making machines.

Edited March 12, 2021 by wefalck

[Bob Cleek]

Actually, in my limited experience, and from the reports of those others with greater experience with this machine, Masa's is the only report of such problems I've heard of. See: 

 

When the instructions are understood and followed, the problems described in this post don't seem to occur. Surely, cutting up the machine and undertaking to redesign it does not seem to have been a productive endeavor. Certainly, this was true with respect to both the substitution of the wooden bobbin axles which did not provide for the slight resistance necessary to keep the thread taunt as its pulled from the bobbins, nor with respect to altering the speed and coordination of the take-up spool. As for the thread tension, that only needs to be sufficient to keep the threads from becoming loose. The degree of tightness in the lay-up is a function not only of the speed of the take-up spool, which is easily adjustable by the speed control knob (and does require a bit of adjustment if the bulk of the laid-up rope fills the spool significantly,) but also of the adjustment of the "wind point" at the cross-bar. (See Alexey's explanation and diagram at post #12 in the thread linked above.) Note that the machine has been improved over time. Notably, the improvements made by the writer of the review above are now incorporated in the machines being made currently.

 

Note the procedure for operation and how the adjustment of the take-up spool speed affects the "wind point" in Domanoff's instructional video.

 

 

 

Edited March 12, 2021 by Bob Cleek

[modeller_masa]

 

As Cleek said, it has felt inside to give smooth friction, but I would say that it is mechanically insufficient. Since I added screw tension on supply bobbin, it rotates like a jammed roller.

 

(source: https://www.compadre.org/nexusph/course/Friction )

 

It can be explained by static and kinnetic friction. Threads have elasticity like rubber band, so cohesive force breaks the maximum static friction point. Unfortunately, it can't continue to draw following thread at low speed and stop again. I would say that the bumpy bobbin happens remarkably at lower speed. As I increase winding speed, it runs much smoother and makes better ropes. Running Domanoff's machine at slow speed with silence may cause worse result than at faster speed.

 

 

Sometimes small businesses don't update minor changes on product manual. Samething happened when I bought the Domanoff SM4 and PL4-4. It is true that I neglected official manuals because I thought the instruction movies are outdated. Now i'm in trouble, so I take your advice and will read all the manuals from the beginning. In addition, I'm a shy person that usually don't ask to manufacturer, but I'll try. 😖

 

 

On 3/7/2021 at 4:20 AM, modeller_masa said:

 

The vibration problem is not significant and Domanoff managed it well. The biggest noise comes from the green box according to my experience. If I change the gear to timing belt, I may be able to decrease 10 dB noise.

 

1. I think I assembled well when I received demounted gears. I'm sure that your machine is more quiter than mine because it is rubber band driven machine. I have long term plan to replace all the gears into pulley and timing belts.

 

2. You're correct. I misread a manual at first and surprised at bumping vibration. All 4 bobbins and bolts must be mounted when 4 or 3 strands works. But omitting with 2 strands works is ok. 😉 (Filled- ( ) - Filled - ( ) )

 

3. I need more words to emphasize the importance of tension control on supply bobbin... 

 

4. I saw that Domanoff's sample thread has the core thread, and its function is kind of adhesive to make a shape as you said. Interesting and difficult concept. 😂

 

5. Thanks for great link! It is great to know that I can move the bars. I was always curious why he made the 'windpoints'. I planned to remove them and make new solid post at first. 🤨 

 

6. Yes. Only one thread I own is right twist thread, so I don't mix it with other threads. I hope 'real' ropes use only left twist threads.

 

You gave me huge helps! I'm sorry I made you leave long answer. I should have asked to Alexey. 

 

(DMC deltelles 80, Cotton 100%, Ecru color, 3 strands)

 

It is still far from the art of rope, but barely acceptable condition in my opinion, so I go back to la recouvrance for now. I'll update a modification log when I add more functions in near future. Thanks very much for useful comments, wefalck, Cleek.

[modeller_masa]

Sorry for wrong post. I misunderstood a concept of this device and performed reckless modification. 

 

I checked all the manual and description, and found that this is a special machine. His manual is very compact, but very dense. I shouldn't have skip some sentences. I believed that this machine can do anything because of the most expensive price, and the self illusion made me to modify it to be an universal machine. I was yelling that my new motor boat is not flying, and was welding wings. 😂

 

 

I followed the instructions, and (heavily modified) Domanoff PL4-4 works pretty well in that way. Most issues I encountered above were out of manual, and some good results I considered as a beginner's luck were as instructed. Equal tension on supply bobbins is a bit frustrating, but I believe I can manage it with simple tool such as spring balance. It is inconvenience as wefalck said, but I want to stick to manual and learn skills now.

 

Thanks again for hearing my pointless complaints patiently. I won't do this next time by reading manuals carefully. 

 

 

The wood bold with R-clip is only valuable result from this project. It works with Domanoff SM4 serving rope machine idealy. I'll report it to Alexey.

 

---

 

wefalck, I thought about multiple spindle motor-computer driven device. It can count every twist and strength of tension in theory. I think it seems like 3D printer. 

Edited March 12, 2021 by modeller_masa

[wefalck]

I once (a long time ago) bought a small pocket calculator, unpacked it and started to type on it wildly - until I ran into a problem. Only then I reluctantly unpacked the manual and on the first page I read this: "Do you also belong to those, who unpack, start typing wildly, resign and then look for the manual ... ?"

 

So, you are not alone ...

[Bob Cleek]

7 hours ago, modeller_masa said:

You gave me huge helps! I'm sorry I made you leave long answer. I should have asked to Alexey. 

No problem at all! I'm happy to have been able to offer a bit of help.

 

You can email Alexey. He uses "Google translate," so language isn't much of a problem. He's a very nice fellow and always ready to answer questions and give helpful advice.