Penn 970/980/990 Plate/screw damage issue possibly solved!!!

[Porthos]

When Jurelometer offered to investigate the possibility of a shim solution to prevent over-tightened screw damage to the plates in this post:

https://alantani.com/index.php?topic=34275.0

I dug out the 970 loose parts and parts reel from the garage. In evaluating what parts Jurelometer would need measurements, the following list formulated:

• one ring (left and right rings are identical probably to simplify manufacturing)
• one frame bar (since the plate screws secure into one of the two holes thru the ring)
• one upper plate screw
• one lower plate/foot screw

Since the parts reel had the plates loosely secured in, I unscrewed every one off during the evaluation, and while I "reassembled" everything back, I noticed that differences existed (see attached pic). That's when the light bulb clicked on!!!

It appears Penn HAD a solution! The upper and lower pair of screws correspond to the upper and lower holes to the bar. The upper screw of each set is only partially threaded (probably a specific name exists for this) while the lower screw is fully threaded (like many screws from other Penn reels). The un-threaded section is of equal length for both upper and lower screws and THAT points to the extreme likelihood that it was to prevent overtightening!!!

Since I got both my 970's used, I can see the possibility that original screws got damaged along the way and the replacements were the more universal plate screws and not ones specific to the Mag Powers. A quick survey of the mysticparts.com page for 970 reveals that no pics exist for the 38-* or 38A-* parts so the visual differentiation of the Mag Power screws was lost with the passage of time. Current Mag Power owners who had their reels from N.I.B. would probably be the best ones to verify this; probably those who got used "mint condition" reels would be able too, but no guarantees.

NOS Penn Mag Power plate screws are probably now made of unobtainium in 2021, BUT since original examples are known to exist and can now be examined, recreating the screws is possible and would be a far easier solution than any shim/new plate/new frame fix.

Hope this helps all Mag Power owners here.

Best.

[thorhammer]

Wai, that's great some great sleuthing! That's called a shoulder, also just partially threaded. We believe they are 5-40, right?  I do have a 990 that I'm the original owner of; when I get a minute I'll check. I also have a 970 gettin pimped (including a double-dawg plate Sal sent me, and a new tail plate from Randy (Rancan) so I'll check those as well.


Maybe Alan C. could look at those- he's making some screws for other things.


John

[mo65]

Great work Wai!

[jurelometer]

Very interesting Wai (spelled it right this time ),

I found photos on Ebay for a 38-970 (Right Side Upper Spacer Bar Screw), and 31-970 (Right Stand Screw).  Both have the extra wide shoulder, as in your photo, with the 31 being shorter.   For this  shoulder with a larger diameter, the clearance hole in the sideplate for these screws has to be larger than the clearance hole in a typical plastic Penn sideplate that accommodates the standard Penn 5-40 screws, so you should be able to verify what was intended to go where.

Note that the shoulder is wider than than threaded portion.  My guess is that this allows the ring to be locked to the spacer bars and stand  with more clamping force than the sideplate to the ring for the same screw (if the if the shoulder length is precise).   But the shoulder screws are used only for the right sideplate (correct?) , which kind of makes me think that this might have been a late stage design correction, where they figured they needed a bit more clamping force on the handle side ring, but could get away with less on the left side and not have to make a new mold for the left sideplate.

If there is a pattern where cracks tend to occur, we might be able to deduce more.   It seems to me that there is enough breakage on these sideplates, that customers substituting the wrong screw in place of the 38-970 and 31-970 would not explain all of  it.  If most of the breakage occurs on the left sideplate, or if the shoulder length was not very precise on the right side screws, then you might be onto something.   Hard to tell as I am doing all of this remotely, never having handled a 970/980. 

I was wrong in my post on the other thread where I stated that the spacer and foot were only attached to the stand.  I will go back and correct when this gets sorted out. 

My guess as to why there is a gap between the bottom of the sideplate and the bottom  surface of the ring is that it it is a much simpler operation to get a true centered, flat fit by mating with the edge/lip of the ring, that can be pretty easily finished to be true and flat. Combined with a tight fit on the ring diameter to the sideplate, there would be a more rigid and aligned fit than the original Bakelite sideplate system.

A Delrin sideplate would be a fun machining project for an amateur machinist.  Delrin is a breeze to machine if you don't get too fussy about surface finish.  The wall thickness might have to be beefed up a little if fiber filled Delrin was not used.

-J

[Porthos]

Hey Dave (Jurelometer?),

From further analysis today, I disassembled my serviceable 970; all four screws from the left side were fully threaded; the handle plate screws are all shouldered but also peened to prevent them from falling out.

My experiment then went as follows:

• The left plate screw holes are too small for the shouldered screw to pass through; hence "standard" screws were used and hence why (as you correctly pointed out) the left plate has more breakage from overtightening,
• I filed down the three peened points on the screw down
• On my damaged left plate I used a round needle file to incrementally expand the remaining intact foot hole until the modified shouldered screw could past through
• I then inserted a standard screw through the adjacent pillar repaired hole for comparative analysis (see attached)

My conclusions are as follows:

• Since all four of the left plate screws are "standard," it seems unlikely that four shouldered screws were damaged and replaced, so the "standard" screws appear to be original factory
• The shouldered screw's shoulder is too deep so the handle side screws cannot to used as a "drop in" solution
• The depth of my pillar repair is probably the more "correct" dimension since it was calculated by subtracting how deep the plate would be once fitted on the ring from the internal depth of the ring's well (?)
• Penn had the solution for the handle side but did not apply it to the left side
• Custom screws produced with the "correct" shoulder depth would be the simplest solution for anyone with intact left plates with minor round needle file work on four holes

None this, of course, will be of immediate help to anyone with an existing broken left plate; they will still require a replacement before getting any benefit from custom screws.

[jurelometer]

Good job Wai!

I would note that  there is always the option of just not tightening the screws to much 

Also, there are two different shoulder screw part numbers, so I assume one is longer than the other.

But if you want to get a bit more clamping force on the spacer and reel stand/foot.  A properly sized spacer (AKA standoff) for each screw will also work.  A standoff in this case is like a tube, but with much thicker walls.

-J