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Cutting down the LF Impulse Mast

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butterfish
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Cutting down the LF Impulse Mast

Postby butterfish » Tue Jul 24, 2018 4:33 pm

Hey

Has anyone cut down the long (94,5cm) original LF Impulse Mast? I want to do it because of shallow water on my homespot. Should finally be somewhere between 70-80cm. The short mast with 60cm seems a little bit too short.

So is there any advice for me? Is it better to cut down the mast on the upper side (where it fits into the baseplate) or on the downside (where it connects to the fuselage).

I have a machine to cut it really 100% straigt. The screw holes can be re-tapped.

Has the mast everywhere the same profile? are there reinforcements inside on the up- or downside of the mast? does it therefore make any difference on which end i cut the mast?

thx for any infos!!!

cheers

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Re: Cutting down the LF Impulse Mast

Postby direnc » Tue Jul 24, 2018 5:11 pm

I have not cut a LF mast, but have some others. Does not matter which end you cut.
Just be sure if you really need another short mast.

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Re: Cutting down the LF Impulse Mast

Postby Laughingman » Tue Jul 24, 2018 5:11 pm

Sure I have done it. I cut mine to 30" and it works good.
I cut the bottom off which I will likely now use the mast upside down because the holes are tapped deeper then my tap will allow.
So here is my advice
1. buy a machine tap instead of a hand tap so you can tap it deep enough accept the longer bolts
2. make sure you get the matching drill as you will need to bore the holes larger before you can tap them
3. plan to use the plugs installed in the end of the mast over again
4. in hind sight I would cut the top instead of the bottom.

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Re: Cutting down the LF Impulse Mast

Postby butterfish » Tue Jul 24, 2018 8:39 pm

Laughingman wrote:
Tue Jul 24, 2018 5:11 pm
Sure I have done it. I cut mine to 30" and it works good.
I cut the bottom off which I will likely now use the mast upside down because the holes are tapped deeper then my tap will allow.
So here is my advice
1. buy a machine tap instead of a hand tap so you can tap it deep enough accept the longer bolts
2. make sure you get the matching drill as you will need to bore the holes larger before you can tap them
3. plan to use the plugs installed in the end of the mast over again
4. in hind sight I would cut the top instead of the bottom.
really good advice!

so i will cut the bottom! i have already a machine to tap the screwholes deep enough.

i only have heard that the new lf mast like on the impulse ffoil is on the top end reinforced - but it sounds that there is no reinforcement.

ahhh - and how to seal the mast after cutting it? might epoxy glue the right thing to do it with?

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Re: Cutting down the LF Impulse Mast

Postby Tony » Tue Jul 24, 2018 8:54 pm

The standard Cloud IX mast is 27", I wonder if that is compatible with the impulse?
Maybe you're looking for more of a difference.
Not sure I've seen it for sale by itself so that may not be an option or may be expensive.
It would be nice to see LF offer some additional mast lengths.

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Re: Cutting down the LF Impulse Mast

Postby Laughingman » Tue Jul 24, 2018 9:35 pm

butterfish wrote:
Tue Jul 24, 2018 8:39 pm


really good advice!

so i will cut the bottom! i have already a machine to tap the screwholes deep enough.

i only have heard that the new lf mast like on the impulse ffoil is on the top end reinforced - but it sounds that there is no reinforcement.

ahhh - and how to seal the mast after cutting it? might epoxy glue the right thing to do it with?
no reinforcement that I can see, the only difference is there is a pin up top but not sure what that is for, but if you can cut the bottom perfectly square and you can tap 2" deep then sure go for it on the bottom. as far as sealing it, just pop out the plugs from the piece you cut off and press them in using a rubber mallet.

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Re: Cutting down the LF Impulse Mast

Postby tegirinenashi » Wed Jul 25, 2018 1:06 am

You don't need long bolts at the plate collar side of the mast. The bolts at that connection are not under any real stress. It is the plate that the mast is pushing against with rider's weight, while collar keeps against twisting and bending.

In fact, you don't need any bolts at all, as you can just epoxy the collar to the mast (but make sure there is no gap between the collar and mast to disable any wobble).

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Re: Cutting down the LF Impulse Mast

Postby Laughingman » Wed Jul 25, 2018 2:56 am

tegirinenashi wrote:
Wed Jul 25, 2018 1:06 am
You don't need long bolts at the plate collar side of the mast. The bolts at that connection are not under any real stress. It is the plate that the mast is pushing against with rider's weight, while collar keeps against twisting and bending.

In fact, you don't need any bolts at all, as you can just epoxy the collar to the mast (but make sure there is no gap between the collar and mast to disable any wobble).
The long bolts are to be used where the fuselage is attached to the mast, not where the base plate meets the mast, and while I realize there is no “strength” benefit past the diameter of the bolt they must have done this for a reason, likely due to vibration, maybe to help the bolt from vibrating lose.

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Re: Cutting down the LF Impulse Mast

Postby tegirinenashi » Wed Jul 25, 2018 4:46 am

Laughingman wrote:
Wed Jul 25, 2018 2:56 am
tegirinenashi wrote:
Wed Jul 25, 2018 1:06 am
You don't need long bolts at the plate collar side of the mast. The bolts at that connection are not under any real stress. It is the plate that the mast is pushing against with rider's weight, while collar keeps against twisting and bending.

In fact, you don't need any bolts at all, as you can just epoxy the collar to the mast (but make sure there is no gap between the collar and mast to disable any wobble).
The long bolts are to be used where the fuselage is attached to the mast, not where the base plate meets the mast, and while I realize there is no “strength” benefit past the diameter of the bolt they must have done this for a reason, likely due to vibration, maybe to help the bolt from vibrating lose.
Bolts vibrating loose is hardly a concern. Certainly, plate connecting bolt can unscrew itself a little, but if foil is connected to the board, it has nowhere to go.

2 long bolts for fuse connection is also not necessary. The front wing lift is leveraged entirely upon the bolt at the opposite side. The front bolt only function is to keep fuse aligned. (This observation has little practical value, though: imagine how bewildered customers would have been if manufacturers were supplying all the bolts of different length:-)

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Re: Cutting down the LF Impulse Mast

Postby butterfish » Fri Jul 27, 2018 8:52 pm

mast is cut down, screw holes re tapped, everything is fine.

how should i seal the aluminium where the mast is cutted? my goal is preventing corrosion in salt water!


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