How many hours for m20k windshield?

[FloridaMan]

Mechanic has just finished my side windows at around 20-22 hours and will start on the windshield when I’m done with my next trip. My side windows up front are 1/16 thicker than factory because of the oversized vents on both sides. He asked me to get some estimates from those have done this so he won’t be too far off on the windshield. My guess is that he expects it to take him longer since it’s his first m20k and wants to be fair. I suspect it’s a bigger job on the K because of that sheetmetal faring on the bottom. 
 

color is solar control gray. 

[jetdriven]

3/16” 10-15hrs.  

Edited November 19, 2021 by jetdriven

[1980Mooney]

20 years ago Lone Star Aero in San Antonio (which used to specialize in Mooney's) invoiced me 15 hours to replace a M20J windshield.  It should be the same as a K.  

[larrynimmo]

To do it right….including repainting it should be at least 20 hours.

I took a full week to get it done

[Guest]

The time required depends on the starting point.  

The lower retaining strip has to be drilled off, someone has to collect all of the rivet tails from behind the instrument panel as the drilling progresses.  Mooney used solid aluminum rivets during production, if yours has been replaced in the field, it may have been riveted in with Cherry max rivets, which are a pain to drill out, and takes longer.  The tails for these have to be collected as well all from behind the panel in amongst all of the wires and avionics.

Depending on how the retainer was bonded in place it may not recover from the process of removal.  The last windshield we did required a new retainer to be bought, fitted and painted, it was the last one Mooney had at the time.

Depending on how carefully the last person did on the drilling and riveting the holes may be oversized.  If you’re unlucky the skins have damage requiring repair.

Riveting it back in place with solid rivets, a two person job.

It all takes time, up to forty hours wouldn’t be a surprise to me.

Clarence

[ohdub]

On 11/19/2021 at 6:46 AM, M20Doc said:

 

Depending on how the retainer was bonded in place it may not recover from the process of removal.  The last windshield we did required a new retainer to be bought, fitted and painted, it was the last one Mooney had at the time.

Was that mine, or was someone else as unlucky as me? 

[PT20J]

On 11/19/2021 at 3:46 AM, M20Doc said:

Depending on how the retainer was bonded in place it may not recover from the process of removal.

Curious if the variation you’ve seen is present in original factory installations or if it comes only from overzealous field installations. 

[jetdriven]

On 11/19/2021 at 6:46 AM, M20Doc said:

The time required depends on the starting point.  

The lower retaining strip has to be drilled off, someone has to collect all of the rivet tails from behind the instrument panel as the drilling progresses.  Mooney used solid aluminum rivets during production, if yours has been replaced in the field, it may have been riveted in with Cherry max rivets, which are a pain to drill out, and takes longer.  The tails for these have to be collected as well all from behind the panel in amongst all of the wires and avionics.

Depending on how the retainer was bonded in place it may not recover from the process of removal.  The last windshield we did required a new retainer to be bought, fitted and painted, it was the last one Mooney had at the time.

Depending on how carefully the last person did on the drilling and riveting the holes may be oversized.  If you’re unlucky the skins have damage requiring repair.

Riveting it back in place with solid rivets, a two person job.

It all takes time, up to forty hours wouldn’t be a surprise to me.

Clarence

Yup. 
we did a 1/4” windshield before the last one.  All the things you’re taking about this has #5 universal head cherry max rivets. We had to destroy all the rivets by cursing and sanding the heads  off and killed the retainer strip also. Milling down the windshield. Then trimming it and fitting the new strip took over 30 hours.  It took 3 days with two people.   It looks great though.  

[201er]

13 minutes ago, jetdriven said:

Yup. 
we did a 1/4” windshield before the last one.  All the things you’re taking about this has #5 universal head cherry max rivets. We had to destroy all the rivets by cursing and sanding the heads  off and killed the retainer strip also. Milling down the windshield. Then trimming it and fitting the new strip took over 30 hours.  It took 3 days with two people.   It looks great though.  

Yikes, that's some job you did!

[EricJ]

Mine's gonna need to be done at some point and it has all flush cherry max rivets holding the retainer.   Not looking forward to that.

 

[jetdriven]

13 minutes ago, EricJ said:

Mine's gonna need to be done at some point and it has all flush cherry max rivets holding the retainer.   Not looking forward to that.

 

I haven’t found a way to remove flush Cherry other than destroying the rivet and whatever it is holding on as well. The bad thing is that retainer strip cost 1000$. 

[takair]

7 minutes ago, jetdriven said:

I haven’t found a way to remove flush Cherry other than destroying the rivet and whatever it is holding on as well. The bad thing is that retainer strip cost 1000$. 

I haven’t done it in years, but, as I recall, if you use a Dremel fiber cut off wheel, you can grind/cut just deep enough to cut the locking mechanism…which is steel….you can then use a center punch and drill to remove the rest of the rivet, with good results and no damage to the material below.  

[ohdub]

1 hour ago, PT20J said:

Curious if the variation you’ve seen is present in original factory installations or if it comes only from overzealous field installations. 

Assuming he was talking about my windows, he told me that my windshield and pilot side window had obviously been replaced at some point and that an incorrect type of sealant had been used. My other windows had the factory sealant.

[jetdriven]

53 minutes ago, takair said:

I haven’t done it in years, but, as I recall, if you use a Dremel fiber cut off wheel, you can grind/cut just deep enough to cut the locking mechanism…which is steel….you can then use a center punch and drill to remove the rest of the rivet, with good results and no damage to the material below.  

That’s the method we use to cut off the universal head cherry max rivets. Destroy the locking collar, punch the stem and then drill out the body. Easy. But the flush ones when you get the cut off wheel deep enough to destroy the lock and collar you’ve already killed the piece that is holding on as well. I’ve had limited success with a 1/8 inch diameter ball style metal cutter on a Dremel tool, but the cutter is not cheap, it takes about 10 or 15 minutes to kill the rivet  enough to drill it, and between the Price of several of these cutters and the time it takes to remove a bunch of rivets it gets expensive to do it that way

Edited November 20, 2021 by jetdriven

[Guest]

8 hours ago, ohdub said:

Was that mine, or was someone else as unlucky as me? 

Without naming names, yes.

Clarence

[Guest]

5 hours ago, PT20J said:

Curious if the variation you’ve seen is present in original factory installations or if it comes only from overzealous field installations. 

I think field installations are worse than factory by a good margin. The factory uses PRC which is challenging to remove, field installs with silicone are way worse.

Factory riveting starts with virgin holes in virgin metal, later replacement depends on the skills and tools the maintainer has.

Clarence

[Guest]

2 hours ago, jetdriven said:

That’s the method we use to cut off the universal head cherry max rivets. Destroy the locking collar, punch the stem and then drill out the body. Easy. But the flush ones when you get the cut off wheel deep enough to destroy the lock and collar you’ve already killed the piece that is holding on as well. I’ve had limited success with a 1/8 inch diameter ball style metal cutter on a Dremel tool, but the cutter is not cheap, it takes about 10 or 15 minutes to kill the rivet  enough to drill it, and between the Price of several of these cutters and the time it takes to remove a bunch of rivets it gets expensive to do it that way

I have a heavy steel bucking bar with a hole drilled in it to receive the Cherry max tail.  Holding it in place where possible then driving out the stem  works in many cases, but it still takes two people and time.

Clarence

[jaylw314]

2 hours ago, M20Doc said:

I have a heavy steel bucking bar with a hole drilled in it to receive the Cherry max tail.  Holding it in place where possible then driving out the stem  works in many cases, but it still takes two people and time.

Clarence

I've used that trick, but you can do it with one person (well, assuming you can reach the other side) if you use a small spring loaded center punch to drive it the stem.  You just need to file down the punch or find one small enough it won't damage the hole

Edited November 21, 2021 by jaylw314

[PT20J]

For what it’s worth, here’s how Cherry says to remove them…

[Ragsf15e]

29 minutes ago, PT20J said:

For what it’s worth, here’s how Cherry says to remove them…

Sounds simple under/behind/below the bottom of the windscreen! 

[jetdriven]

Notice they use a universal head rivet in this instruction drawing.  I tried this a bunch of times  before I realized it’s pretty much impossible to try to drill a hardened steel stem that’s  smaller than the bit you’re using that’s surrounded by a nice mass of soft aluminum. The drill bit slips off of the stem, then hits the body of the Rivet and then figure eights the hole and trashes the part.  

Edited November 21, 2021 by jetdriven