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Repairing A=Cat mast

Posted By: TheManShed

Repairing A=Cat mast - 08/11/09 04:15 AM

Repairing a mast this week.

I started with making a stand to hold the mast level.

A few scraps of biax e glass and the mast taped off with 2 layers of wax paper. Sail groove taped of good to stay clean.

Long view made two clamps of biax on the groove side up so clamps would come off of the mast. This side is also straigh and the taper will not bother the alignment.

Wetted out the glass with epoxy using a cheap throw away paint brush.

Attached picture Simple Lay-up.JPG
Attached picture Long view lay-up.JPG
Attached picture Wet out.JPG
Posted By: TheManShed

Re: Repairing A=Cat mast - 08/11/09 04:21 AM

The next step was to trim up the clamps then mount them on stands made from scrap wood. I screwed the clamps to wood and put duct tape over the screw heads to protect the mast. I mounted the mast and clamped the base boards to the table to make the mast would not go anywhere if bumped in the shop.

Attached picture Stands.JPG
Attached picture Mast stand.JPG
Attached picture Fiberglass clamps.JPG
Posted By: TheManShed

Re: Repairing A=Cat mast - 08/11/09 04:33 AM

Last post for the night.

Looked at the break, clean up the area where it was deformed.

Tomorrow I'm building a "bong" for the vacuum pump and mounting it on a base with fittings, Then bagging out the first sleeve in carbon fiber.

The sleeve will have two sizes - on the main mast section the opening is 50mm and on the top part it is 55mm. There was a 5mm hard step at the break. Usually you do not want a hard step (spot) in fiberglass it is better to taper off any size difference. Case in point here at the break. It created a hard spot in the mast. It is not going to be an easy fix but I can come up with something.


Attached picture Goes together like this.JPG
Attached picture Break.JPG
Posted By: cyberspeed

Re: Repairing A=Cat mast - 08/11/09 04:48 AM

Cool Stuff. Can't wait to see the finished product.
Posted By: Anonymous

Re: Repairing A=Cat mast - 08/11/09 01:26 PM

Mike, thanks for all the step by step and pics...
Posted By: bvining

Re: Repairing A=Cat mast - 08/11/09 01:53 PM

Mike,
I see in the pics you have some fiberglass cloth, and you mention fiberglass in your posts. Are you going to use glass in the final repair? I would recommend using only carbon cloth and epoxy as thats probably what the mast was made from originally.

I'd also recommend taking the diamond wires off so the mast isnt under tension and straight when you repair it.

I've made sleeves to repair carbon masts in the past, it helps align the broken sections and adds some structure to the inside of the mast so you dont have so much of the repair on the outside. I made my sleeves using a bladder, I've talked to other guys that have made molds of the inside of the mast using casting wax.


Bill
Posted By: TeamChums

Re: Repairing A=Cat mast - 08/11/09 02:53 PM

Just a guess but is that Dr. Ferber's mast?
Posted By: Robi

Re: Repairing A=Cat mast - 08/11/09 06:16 PM

Originally Posted by TeamChums
Just a guess but is that Dr. Ferber's mast?
Mark Herendeen's
Posted By: TheManShed

Re: Repairing A=Cat mast - 08/12/09 01:31 AM

Few answers;

The repair will be carbon fiber only with west system epoxy and vacuum bagged. Any auxiliary glass work will be scraps of E-Glass. This rig has a cool "on the fly" tension adjustment arm for the diamond wires. They are slacked and the way I’ve supported the mast the diamond wires are in a neutral position if they were not slacked. The mast is level and will be check with a laser to make sure it is straight.

I’m making a sleeve but it is not such a straightforward operation. From the break down towards the foot of the mast the ID of the mast section is 50mm and the wall thickness is 5mm so using a 1:10 taper the outside skin will taper out to 50mm for the repair. This brings me into the slot for tang for the mast hounds. From the break towards the top of the mast it has an ID of 55mm and a skin thickness of 2.5mm. Using the same formula a taper of 25 mm. It has a hard spot that took the skin thickness from 5mm to 2.5mm with a hard drop and this is where it broke. My goal is now to sleeve the mast, which will take two different size sleeves where one will almost fit inside the other and try to eliminate the hard spot. There is also another sleeve further up where I can see some fatigue starting.

The repair will be inside and outside. My plan of lay-up will be in the area of the crack to taper all the way to the sleeve. At least one layer of cloth in the taper at a 45 degree angle to the break in each direction to form a X to try and mend the area around the circumference, all other lay-up will be with the fiber oriented with the mast from top to bottom. Because this mast is broken my main concern is to have a good repair and be strong. You can have the lightest mast in the world but when it is in two parts what good does it do you? Once they break you have to fix them stronger.

Another interesting note is the mast looks like it was spun carbon strand then covered with a carbon cloth exterior lay-up. I’m not sure if I’m looking at a factory mast or modified. I’d be interested in actual construction / lay-up of the mast.
Posted By: Jake

Re: Repairing A=Cat mast - 08/12/09 02:30 AM

Mike,

Tons of fun watching - thanks for the updates. The mast is probably woven fabric on the inside and outside with a bunch of uni running vertically on the inside. Interesting that it has such a huge thickness step there - no doubt that created a stress riser leading to the breakage.

What brand is that stick?
Posted By: bvining

Re: Repairing A=Cat mast - 08/12/09 01:04 PM

Mike,
Is this the mast for the Tri?

Or is it going back into the Acat class? If its an Acat mast, the current trend is toward stiffer masts. The big top sails need stiffer masts. Most guys are adding uni on the outside, oriented top to bottom to stiffen up the mast. If you knew the age and make of the mast, you might be able to get an approximation of the stiffness.

Bill
Posted By: TheManShed

Re: Repairing A=Cat mast - 08/12/09 09:25 PM

I have a special mast for the tri it is still a virgin!

This is for a A-Class cat. So after my repair the mast will be updated! I was working on the resin bong last night. My first bongs were made of bamboo in the late 60's and now they are PVC.
Posted By: TheManShed

Re: Repairing A=Cat mast - 08/13/09 05:29 AM

I have the vacuum bagging bong ready. These works as a vacuum reservoir so I can pull a vacuum and turn the valve then turn the pump off. It also collects any run-off resin and keeps it out of the pump. All the materials were purchased at Home Depot except for the pump and the gauge; they were purchased at Harbor Freight Sales.


Description: Removing AC fitting
Attached picture Vacuum pump Handle removed to get at fitting.JPG

Description: Now I can use Tubing
Attached picture AC fitting replaced with tubing barb.JPG
Posted By: TheManShed

Re: Repairing A=Cat mast - 08/13/09 05:32 AM

more:

Attached picture holes drilled in 4 inch PVC end cap.JPG

Description: Hole bogged in with West and 404 filler
Attached picture Holes PVC tubes bogged in with west epoxy.JPG

Description: Inside bogged
Attached picture Inside bogged.JPG
Posted By: TheManShed

Re: Repairing A=Cat mast - 08/13/09 05:34 AM

more:


Description: Routed up to keep resin away
Attached picture Intake to pump routed up.JPG

Description: Added tube for waste to run down into the bong
Attached picture Waste exhaust tube added.JPG
Attached picture looking inside after the cap is mounted on tube.JPG
Posted By: TheManShed

Re: Repairing A=Cat mast - 08/13/09 05:38 AM

more:


Description: Manifold, vacuum guage fitting, shutoff valve, connections
Attached picture Building manifold.JPG

Description: Front view
Attached picture Resin Bong back.JPG

Description: Front
Attached picture Resin Bong front.JPG
Posted By: TheManShed

Re: Repairing A=Cat mast - 08/13/09 05:39 AM

Starting to work on the Mast. Tomorrow I will start on the sleeves now that I can vacuum bag.


Description: Reshaping mast around the hound.
Attached picture Starting to reshape the spar.JPG
Posted By: Jake

Re: Repairing A=Cat mast - 08/13/09 12:35 PM

Mike,

Nice setup on the vacuum. Note, however that the pump will not hold the vacuum on it's own if you turn it off - it will bleed back through the vanes and discharge your reservoir.. a check valve at the discharge of the pump, or better yet, a electric 3-way mac valve will seal off the vacuum pump when it's off. By nature, the check valve with it's ball and spring will cause a slight reduction in the ultimate vacuum you can pull (which I didn't like when I used one) - so I now use an electronic three-way mac valve to disconnect the pump from the system coupled through the same relay I used to cycle the pump on and off...which then leads to another issue where you need some additional electronics to make everything work together....

A vacuum controller switch coupled with a relay will automatically turn your pump and the valve on and off at a set vacuum level...I've even got one wired into a small PLC controller so I can control all the timing of the valve, pump, switching on and off, and I even programmed in a timer controlled by a series of switches (in a binary fashion) so I can set the controller to not turn the pump on after 1 to 9 hours (so I can go to bed or leave town and rest assured that it won't stay on indefinitely). The next step is to connect a modem to the PLC so it will call me if my pump stays on for more than 15 minutes (indicating a leak occured in the bag)...


just kidding on that last part although it IS possible!.

If you put a small reservoir between the pump and the mac valve, the pump will also have the opportunity to start from ambient pressure instead of being hit with vacuum immediately.

Lots of plans and all the pieces parts needed can be found here:

http://www.veneersupplies.com/default.php?cPath=60_36

One last thing...I had my vacuum switch powering my relay with AC power initially but I had a lot of trouble with bouncing of the switch (making the pump turn on and off very rapidly for a second before it reached steady state). I would recommend using a 12VDC relay (instead of 120VAC) and a wall mounted power supply for the vacuum switch and relay. The relay then can switch the 110VAC to the pump and the valve. Apparently the amount of AC current needed to switch the relay creates magnetic currents that disrupt the sensitive vacuum switch.

I know this is complicated, but compared to the alternative of leaving the pump on full time, it is amazing once it is all together.


Then again, these pumps are designed to be left on for extended periods...so it's not a big deal if you leave the sucker on for hours (although mine does tend to overheat).
Posted By: TheManShed

Re: Repairing A=Cat mast - 08/13/09 01:38 PM

Jake,

Great idea I'll have to explore that I may pick your brain some more. With the check ball I held a vacuum for a hour with the pump off last night.
Posted By: Jake

Re: Repairing A=Cat mast - 08/13/09 02:40 PM

I didn't realize you had a valve after the pump - that should work well.

I've never had a bag that was completely sealed - I've been close where the pump would come on only once every 30 minutes for about 30 seconds...but it was something that I would otherwise have to constantly monitor.

I do like your resin separator ability in your reservoir - I'll be copying that!
Posted By: Clayton

Re: Repairing A=Cat mast - 08/13/09 02:49 PM

Do you have to make another resin separator for each time you use it? Or is the amount of resin collected not an issue? You would think the resin would harden in the hoses and collector making it a one use item.

Clayton
Posted By: pgp

Re: Repairing A=Cat mast - 08/13/09 02:50 PM

You can find small leaks with a stethoscope. It may take a little time; don't ask me how I know.
Posted By: Jake

Re: Repairing A=Cat mast - 08/13/09 03:17 PM

Originally Posted by Clayton
Do you have to make another resin separator for each time you use it? Or is the amount of resin collected not an issue? You would think the resin would harden in the hoses and collector making it a one use item.

Clayton


At least for me, ideally you don't get any resin back into the tubing. With a perforated bleed layer over the lamination coupled with a layer of felt, the excess resin should be captured within the bag. The felt performs double duty by first allowing full distribution of vacuum inside the bag (the bag / laminate would otherwise tend to seal itself) and absorb excess resin.

However, if you are infusing, you don't use the perforated / peel ply or the felt and you will most certainly get some resin back in the tubing. You throw away the saturated tubing when done. You can line the reservoir with a bag or place a small bucket/cup inside to catch the resin as it drips in (assuming you can open it once sealed). Mike's PVC reservoir is nice for this purpose - he can just cut it off and glue a new bottom in the reservoir with a union (though it would be nice to be able to see inside...but I'm not sure how you do that without some expensive acrylic tubing)

Posted By: dave mosley

Re: Repairing A=Cat mast - 08/13/09 03:38 PM

Originally Posted by Jake
Mike,

Nice setup on the vacuum. Note, however that the pump will not hold the vacuum on it's own if you turn it off - it will bleed back through the vanes and discharge your reservoir.. a check valve at the discharge of the pump, or better yet, a electric 3-way mac valve will seal off the vacuum pump when it's off.



In the medical field we use a "water seal system" for chest tubes. It creates a negative pressure system for reinflating the lungs after puncture or surgery(The lung cavity has a negative pressure which keeps the lungs inflated as opposed to the notion that air inflates them positively), but anyway once suction is applied to the water seal system, it cannot bleed back thru the water to lose the pressure. I suppose a check valve does the same, but the bong with a water filled chamber between the pump and the seal may suffice for cheap.

I had the same question about bleed back of extra resin into the bong...does it collect there and harden, or is there a relief for the resin to pour out?

Thanks for all the info, keep it coming
Posted By: TheManShed

Re: Repairing A=Cat mast - 08/14/09 03:07 AM

One of the main reasons is to keep any extra resin away from my pump. Lay-up on a 20’ hull with two skins of carbon and some spots 4 skins in tropical heat will have to be fast so if a little extra epoxy goes on it will be bagged out into the felt, if the felt fills it will go into the reservoir. That is not the plan to suck epoxy into the reservoir like Jake says .........but when do things always go according to plan?

The resin that may go into the tank will just harden in the bottom. At some point if it clogs the reservoir you can cut the bottom off and add a new piece of PVC.

I used clear tubing from the manifold to the pump and resin checked the tubing to see if it melts. The tubing worked well and I actually peeled the resin off of it. I will also use the clear tubing from the mold to the reservoir so I can see if I have epoxy flowing out of the mold. The clear plastic tubing is about $5 for a 10’ roll and should be reusable because it will be in upwards bends so the resin will flow through it, not sit in it.

The water seal sounds good, and from what I hear, bongs had water in them but with the vacuum created on these systems it would suck the water right into the pump.
Posted By: TheManShed

Re: Repairing A=Cat mast - 08/14/09 03:32 AM

Thanks Pete I don't have a stethoscope but I use a piece of tubing. I use to tune twin SU's carbs on my MGA the same way.

The vacuum held for an hour then I opened it up because I went to bed and wanted to lock the pump up in the shop.

Now if the rain stays away this week-end. I've got two week-ends before my shoulder surgey to finish the mast and get the first lay-up on the TMS-20. Then I will be injured reserved for 1 - 2 months.
Posted By: pgp

Re: Repairing A=Cat mast - 08/14/09 12:21 PM

You're welcome. You do realize what you've started with this "ManShed" thing? So far I've thrown out two big bags of crap that were hiding my work bench and added three new sets of shelves. Soon, I'll actually be able to do some work!
Posted By: David Parker

Re: Repairing A=Cat mast - 08/14/09 02:03 PM

Quote
...I've thrown out two big bags of crap that were hiding my work bench


Terrible mistake! You know exactly what will happen. You will immediately need something that you just threw out.

MANLAW: NEVER throw anything away that is remotely useful. (build a bigger shed, a ManShed!)
Posted By: waynemarlow

Re: Repairing A=Cat mast - 08/14/09 08:39 PM

Originally Posted by TheManShed
Few answers;

From the break down towards the foot of the mast the ID of the mast section is 50mm and the wall thickness is 5mm so using a 1:10 taper the outside skin will taper out to 50mm for the repair.


Carbon Uni repairs are notoriously difficult and with your method you will get a very unique bending of the mast under load. The repair chamfer angle for most manufacturers carbon Uni strand is 100:1 and not 10:1 and to maintain strength to adhesion correctly this should be attempted as well as possible. From a practical point it is nearly impossible to do on a round surface. Best of luck but do not be dissapointed at the bend characteristics of the repaired mast as from experiance it is very very difficult. smile
Posted By: TheManShed

Re: Repairing A=Cat mast - 08/15/09 08:02 AM

Thanks for the information Wayne. I have room for a 100:1 taper.

Pete is that a bad thing?
Posted By: pgp

Re: Repairing A=Cat mast - 08/15/09 01:37 PM

laugh Not at all!
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