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 Post subject: rachet and pawl material
PostPosted: 04/28/10 15:52 • # 1 
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Guide

Joined: 10/15/09
Posts: 204
Location: Rio Rancho, NM
Spring arrived and trout season opened, so I have been fishing my first reel.  But rachet and pawl wear is a problem.  Can anyone suggest a better material combination?
Image
The first set was 360 brass for both rachet and pawl.  After a few hours I opened the reel and found brass dust, with obvious worn notches on both sides of the pawl.  The rachet was made by cutting 60 degree notches on the periphery of a blank, and the pawl wear was just where its tip impacts the sharp edges of the rachet.
So I made a new pawl of 303 stainless, but retained the brass rachet.  After a few more hours, I opened again and found more brass dust (photo above), but no obvious pawl wear.  Time to try a new rachet.
I have already obtained a gear cutter in hopes of reducing the sharpness of future rachet teeth.
Another factor may be my spring; it is long and compliant, and has to have a preload in order to stay seated in the groove on the back of the pawl.  I stretch it about 0.100 inch to fit in the groove, and this provides a force of 10 oz on the back of the pawl.  When reeling in, the spring is extended another 0.010 or 0.020 inch, increasing its force to 11 or 12 oz.  When paying out, the additional extention is 0.030 or 0.040 inch, so it may reach 14 oz.  The longer moment arm when paying out makes a notable difference in crank effort required.  I have been studying the pawl design recently posted by eotr.  He uses a much shorter wire, but of nearly the same diameter (0.026).  His arrangement appears to need no spring preload.

Blog: http://northbranchreels.wordpress.com


Last edited by dave49 on 12/30/19 20:41, edited 2 times in total.

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 Post subject: rachet and pawl material
PostPosted: 04/29/10 05:18 • # 2 
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Guide

Joined: 10/15/09
Posts: 204
Location: Rio Rancho, NM
(as of Aug 2011, the replies of Brent (eotr) are missing from this forum)

Brent,
I could listen to the rambling all day.  Thank you for responding.
I am a little hesitant to take on either of these two bronzes due to their hardness and known difficulty in machining.  But I do have some 642 aluminum bronze, not as hard as these, but easy to machine.  Certainly it will be better than 360 brass.
You correctly guess that my reel is noisy.  The back plate is 0.100 thick Delrin, and it amplifies the impact sounds.  So the idea of a PEEK (or perhaps Torlon) pawl is attractive for several reasons.  Recently Michael Hackney (The Reelsmith's Primer) was in nearby Grayling MI and looked at my reel.  His immediate reaction was to suggest a pawl softer than the rachet, in order to improve the wear situation.  This went against my gearing experience, wherein pinions are usually made harder than the mating gears.  Having now heard from two sources, I have to try it.
One more question, did you use a filled grade of PEEK (glass or carbon)?
Dave

Blog: http://northbranchreels.wordpress.com


Last edited by dave49 on 08/30/11 11:16, edited 1 time in total.

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 Post subject: rachet and pawl material
PostPosted: 04/29/10 07:09 • # 3 
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Master Guide

Joined: 08/06/07
Posts: 426
Location: Groton, MA
Great discussion!

Dave, I did look up the coefficient of friction of brass on steel (no specific alloy so it could vary) and it was lower than brass on brass and steel on steel when lubricated. However, surface finish and the geometry does play a big role and I think Brent's comment about rounding the tip of the pawl is right on. After taking a closer look of your photos, your pawl is rather sharp. That might result in a scraping action as it rides over the click wheel "teeth". A rounded/blunt point would make a better bearing surface. I suspect your wear is more an issue of geometry than materials.

As you know, a pinion and spur gear need to transmit load and the involute gear design allows a point contact between the meshing teeth to transmit that load with minimal friction. It makes sense that the pinion be of steel since there is less "web" to hold the pinion teeth. Under high load, there would be a lot of stress in this area. I have had the good fortune to disassemble and scrutinize a number of very old (late 18th to mid 19th century) multiplying reels and many of them have brass pinions and gears that show very little wear. The stress on these parts is generally low (even with a big fish!) so brass worked in this application.

A click & pawl drag on the other hand, is supposed to increase friction. Think about when you were a kid how you attached a cardboard playing card to the fork of your bicycle with a clothes pin so it clicks against the spokes. The card rarely wore out even though it was rubbing against steel spokes. The geometry of the spoke (round) and angle of the card (the longer pawl Brent suggested) along with the lower friction the wax coated card provided resulted in little wear.

Brent's comment about the pawl being easier to replace is reasonable too. Many click & pawl reels came with an extra pawl (and even spring) to replace the original if needed. I have a growing collection of old reels and all of them with a simple click & pawl drag are quite noisy. The ones that aren't do not use the click to apply the drag. For example, the Orvis CFO has a disk drag on a 2nd gear that mates with the main gear. The click is purely aesthetic and the pawl can be removed with no performance loss. This is true on an Ari 't Hart reel I have with a Delrin click wheel and a steel wire pawl that has a most pleasant sound.  But the click wheel and pawl do not provide the drag. Several other modern reels in my collection are similar. I would be very interested in hearing (no pun intended!) of a click & pawl drag that is not terribly noisy.

Dave has built a nice little click & pawl test bed. I am building a similar tester now so I can try different materials and designs and run them in with an attached motor. This should really help bring a little science to the art.

cheers,
Michael

Reelsmith, Author & Publisher
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 Post subject: rachet and pawl material
PostPosted: 04/30/10 06:22 • # 4 
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Member

Joined: 12/18/09
Posts: 16
Great discussion!

For my click pawl reels I have used combinations of  SS for gears and pawl to Delron. Latest has been a combination of Delron AF for the gear and Turcite for the pawl. I like the sound of that combination.
For the pawl, I found as, Dave suggests, rounding of the point helps make things work easier as the pawl is used as the drag. Cut my gears with an 14 1/2 involute degree gear cutter.

Best,
Leroy.........
 


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 Post subject: rachet and pawl material
PostPosted: 08/22/10 10:47 • # 5 
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Guide

Joined: 10/15/09
Posts: 204
Location: Rio Rancho, NM

My blog has a new entry, comparing various plastics.
http://northbranchreels.wordpress.com/2010/08/22/results-of-pawl-wear-test/


Blog: http://northbranchreels.wordpress.com


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 Post subject: rachet and pawl material
PostPosted: 08/22/10 13:29 • # 6 
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Master Guide

Joined: 08/06/07
Posts: 426
Location: Groton, MA
Nicely done Dave, thank you for sharing. I've noticed that natural Delrin machines nicer than black as well. I suspect the black color is achieved by mixing in carbon and that would change the properties - pure speculation on my part but it should be easy to find out.

Cheers,
Michael

Reelsmith, Author & Publisher
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 Post subject: rachet and pawl material
PostPosted: 09/06/10 02:12 • # 7 
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Joined: 10/15/09
Posts: 204
Location: Rio Rancho, NM
Now I find that the gearmotor that I used to test plastic pawls is misoperating.  This makes the data suspicious.  A new blog entry explains the situation.
http://northbranchreels.wordpress.com/2010/09/06/the-gearmotor-that-wasnt-a-gearmotor/

Blog: http://northbranchreels.wordpress.com


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 Post subject: rachet and pawl material
PostPosted: 09/08/10 13:10 • # 8 
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Joined: 12/08/06
Posts: 267
For my first attempt I used tobin bronze gear and mild steel pawl. No more than 1 minute of winding produced
bronze dust. Second attempt was stainless gear and carbon steel pawl. No wear but they are loud and so I have
eased up the tension of the spring.


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 Post subject: rachet and pawl material
PostPosted: 11/16/10 13:06 • # 9 
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Joined: 10/15/09
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Location: Rio Rancho, NM
I bought a better gearmotor and re-did the tests.  The measured wear is similar to that of the first test.  More detail on my blog, http://northbranchreels.wordpress.com/2010/11/16/pawl-wear-test-redone/

Blog: http://northbranchreels.wordpress.com


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 Post subject: rachet and pawl material
PostPosted: 11/16/10 18:48 • # 10 
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Master Guide

Joined: 08/06/07
Posts: 426
Location: Groton, MA
Thanks for the update. It looks like your original tests weren't bad after all but it made sense to remove the uncertainty.

I have some 1/8" sheet nylon if you want to give it a try I'd be happy to send you a piece.

Are you planning to do any tests with metal on metal but change the geometry of the pawl and/or ratchet?

Cheers,
Michael

Reelsmith, Author & Publisher
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 Post subject: rachet and pawl material
PostPosted: 11/17/10 11:56 • # 11 
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Joined: 12/15/05
Posts: 323
Hey guys, I'm glad this topic has risen back to the top. It's brought up quite a few thoughts and observations I've made from my own reel work.

My first thought is why not take a more serious engineering type approach to this problem instead of blind trial and error?

1. Figure out what is ACTUALLY happening in the system.
2. Analyze and prioritize the significance of the factors.
3. Design around the criteria discovered in step 2.
4. Build, test, analyze and reapply new knowledge to step 1.

Here are some of my thoughts on this. It seems like there is a fundamental misunderstanding of the dynamics of the gear and pawl system. And that stems from the speed of the process. When analyzing a gear and pawl system its easy to think of it as a gear mesh where the pawl rides into the root of the gear between two teeth. But, this is only the case when the gear is rotating very slowly. On my spey reel I used a 30 tooth gear. Typical speed for reeling line in is about 2-4 rotations per second, and the speed for pulling line off either by hand or with a fish running is usually much faster. That corresponds to 60-120 teeth passing the pawl PER SECOND, and that's on the low end of the spectrum.

When the gear is rotating at these speeds, the pawl does not have time to completely ride into the the root between the gear teeth. Instead, as the gear rotates and the tip of the pawl slips past the tip of the first tooth, the flank of the pawl impacts the tip of the next tooth. The particles found inside the reel are more likely to be from brittle failure of the material (pitting and flaking) from the repeated impact of the pawl and gear than from a abrasion or grinding-like action from the pawl and gear rubbing against each other. Obviously there is some friction going on, but the more important factor is the impact. Understanding what is actually going on in this dynamic system will help reveal the more important design criteria. Once you have a better understanding of the operating conditions, you still have the design considerations to make: Material, and Geometry.

I think the second is a more simple choice. By choosing a gear and pawl system we automatically constrain ourselves to a narrow window of geometries that will work effectively. But the important part is the minor details that can make a big impact. Here, the shape of the pawl and gear tooth comes into play, most importantly the the very tip of the gear tooth. A sharp tip to the gear tooth -- whether on a gear with an involute profile or a triangular profile -- will concentrate the impact force on the pawl's flank and accelerate the failure of both components. Once the surface integrity of either part is compromised (by very minor pitting and flaking) the effect begins to snowball. Even a small radius on the points of the gear teeth (and the pawl to a lesser degree) will enlarge the surface area of contact and make a pretty dramatic reduction in the amount of wear.

Knowing that the impact is the most important factor makes the material selection a more straight forward process. Toughness as opposed to hardness or strength is by far the most important material property. Some materials (Steel in particular) have an inverse relationship between strength or hardness and toughness. With tool steels, the strength increases with the hardness, but the toughness decreases and the material becomes much more brittle. A good tool steel hardened to somewhere in the middle of its range produces a material that is tough enough to withstand millions of cycles of impact and hard enough to withstand whatever abrasive wear conditions may be present.

I was just cleaning and inspecting my spey reel over the weekend. I used it for 14 days straight steelhead fishing in BC, where I was constantly pulling out and reeling in line. I even had a few fish pull some line out for me. I had been playing with the reel for several months, but this was my first time actually putting it to serious use. What I saw basically confirms everything I've outlined above.

I used A2 tool steel hardened to about 45 Rc for BOTH the pawl and the gear. What I noticed is some very slight polishing on the flanks of the pawl and some very slight polishing on the tips of the gear teeth. But there was no obvious wear or degradation of either of the parts.

The observation of the slight polish to the contact surfaces brings up one more thought, which is that no matter what care we take in the manufacturing process to smooth out any sharp edges, etc. there is still going to be a "breaking in" process that goes on.

Just some thoughts and observations,

Mark

Mark Shamburg

Confluence Rod Company - Maker of Single and Double hand Bamboo Fly Rods and Click-Pawl Reels

Confluence Guide Service - Providing Swing-Only OP Winter Steelhead guide trips

http://www.confluencerods.com/

On Instagram @shammygram


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 Post subject: rachet and pawl material
PostPosted: 11/17/10 12:52 • # 12 
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Master Guide

Joined: 08/06/07
Posts: 426
Location: Groton, MA
Some great thoughts and observations Mark. I don't use an involute gear shape on my "gears" since that geometry is not needed for this application for the reasons you point out. I think some reel makers purchase precut gears to use as the "click" simply because they are available.

I came to the same conclusion regarding the shape of top of the tooth (rounded) based on looking at 100s of antique reels that span 150 years or so and my own experience. The other variable I would add is friction. The friction comes to play as the side of the pawl slides over the top of the tooth. There are both mechanical and material properties contributors to this friction. Here is a chart of Coefficients of Friction for various combinations of materials dry and lubricated. Of course this does not take into consideration the various alloys, etc but it does provide some interesting insights. Even the old mechanisms were lubricated and that has a big effect on wear too.

For most of my own work, I observe the classic reels that survived (some with heavy use) and mimic their geometries and materials. Of course, today we have a lot more engineering knowledge and that is sometimes contrary to the empirical methods employed in the past.

Cheers,
Michael

Reelsmith, Author & Publisher
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 Post subject: rachet and pawl material
PostPosted: 11/17/10 13:42 • # 13 
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Joined: 12/15/05
Posts: 323
I agree that looking at classic reels that have survived years of heavy use is a useful tool. That's part of the reason I used hardened tool steel.

I didn't discount friction, I just don't think it's nearly as important as the impact. Depending on the configuration of the system, the pawl may rebound slightly after striking the gear tooth and not even be in contact with the gear tooth as it rotates by. The lubrication, is certainly important to reduce any friction that may occur, (which is certainly not non-existent) and it can also help to cushion some of the impact force.

I do think there is some merit to the involute profile, depending on the pitch and pressure angle and configuration of the system as it may provide a larger surface area for the pawl to strike. But I don't think the advantages of the involute profile are necessarily worth the extra cost and work to produce.

Mark

Mark Shamburg

Confluence Rod Company - Maker of Single and Double hand Bamboo Fly Rods and Click-Pawl Reels

Confluence Guide Service - Providing Swing-Only OP Winter Steelhead guide trips

http://www.confluencerods.com/

On Instagram @shammygram


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 Post subject: rachet and pawl material
PostPosted: 11/18/10 07:03 • # 14 
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Joined: 10/15/09
Posts: 204
Location: Rio Rancho, NM
Mark,
Thank you for your extensive remarks,  I can agree with most of what you have said.

What little data I can find on toughness does not show carbon steel to be superior to many other materials; http://tap.iop.org/mechanics/materials/file_39561.doc.  What makes your A2 pawl much better than the brass pawl that I made is likely a combination of strength and toughness.  And coefficient of friction has some influence.  I suspect that the low speed of my tester tends to emphasize the importance of friction. We need a pawl material with a certain combination of properties, but selection is not straightforward.  

Your success with A2 steel is an important empirical result.  Please remark on your heat treat procedure. 

Please give us some detail if you have a practical procedure to produce round corners on rachet teeth.

On the examination of old reels, we may suspect that the rachet is steel (particularly if it has rusted), but how would we determine the alloy or hardness?

I do not consider comparative tests of materials to be "blind trial and error", and I encourage anyone who has tested any potential reel materials to share the results.  I think that fits in the scope of this forum. 

Dave

Blog: http://northbranchreels.wordpress.com


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 Post subject: rachet and pawl material
PostPosted: 11/18/10 08:11 • # 15 
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Joined: 12/15/05
Posts: 323
Dave,

One quick and simple way to see if a piece of steel has been hardened is to try to file it. A file will not do much to moderately hardened steel and will not touch very hard steel.

Beyond that, it requires a hardness tester to determine the actual hardness. As for determining the alloy, that requires far more sophisticated equipment than I have access to.

One of the reasons I chose A2 tool steel as opposed to others is that it can be easily hardened at home. By heating the material until it is cherry red and allowing it to air cool you can achieve hardness of upwards of 60Rc. However, by quenching the part in water you get a hardness in the range of 40-45 Rc, which is much more desirable for our applications.

For rounding the edges of the gear teeth you can turn the gear in the lath and use sandpaper to knock the sharp edges off. Make sure to run in reverse for the same amount of time as forward.

Mark

Mark Shamburg

Confluence Rod Company - Maker of Single and Double hand Bamboo Fly Rods and Click-Pawl Reels

Confluence Guide Service - Providing Swing-Only OP Winter Steelhead guide trips

http://www.confluencerods.com/

On Instagram @shammygram


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 Post subject: rachet and pawl material
PostPosted: 11/19/10 16:39 • # 16 
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Sport

Joined: 12/31/07
Posts: 69
I second the thought on using A-2 tool steel for that gear. Brass is way to soft. I started using 410 stainless steel on all my new reels I am happy with the material its just $ and heat treating needs to be done by a pro. After you make the switch to the gear that wear will be where?. This is how I test my reels. But again my reels hate meImage?


Tim
The Spey Company

Tim Pantzlaff

The Spey Company
1852 Allouez Ave
Green Bay WI
54311

http://speyco.net/

tlpantzlaff@sbcglobal.net

Cell: 1-920-227-5574


Last edited by speyco on 11/19/10 16:43, edited 1 time in total.

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 Post subject: rachet and pawl material
PostPosted: 08/23/11 15:56 • # 17 
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Joined: 10/15/09
Posts: 204
Location: Rio Rancho, NM
I have now been able to test Delrin and hardened steel under identical conditions, see http://northbranchreels.wordpress.com/2011/08/23/pawl-testing-at-higher-speed/.  When longevity is the criterion, Delrin is the better choice.
The steel is not A2 tool steel, but 416 stainless, which has a slightly higher Charpy test value.  It is quite similar to the 410 stainless used by Tim, but has "free machining" additives.  The Charpy test value for 416 is lower than that of 410; I assume that this is due to the additives.

Blog: http://northbranchreels.wordpress.com


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