Nyitra I

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cyberbadger
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Re: Nyitra I

Post by cyberbadger » Thu May 25, 2017 3:37 pm

SL Ethel wrote:One striking thing I noticed in your narrative is "plenty of steam". Many, if not most, of our plants, have engines that can swallow more steam than we can produce - essentially we're boiler limited. If you are only turning 60 RPM and can keep steam pressure all the way up, you definitely have room to develop more horsepower and (probably) speed. I would think about 200 rpm as a comfortable slow cruising rpm for your engine, which is probably comfortably capable of at least double that. If you have enough steam for 200 rpm, you'd approximately triple your power output. Something to think about when doing the belt replacement - maybe adjust the ratio a bit at the same time and see if it gives you another knot.
Well the maiden voyage I was belt slip limited, the second wingfoot lake I was seaweed limited, and this 3rd trip I was just getting up to pressure, maybe 100-150psi, and then snap. :)

The second wingfoot lake the safety valve had to pop maybe 10 times because we couldn't use all the steam we were making! Exercising your safety valve at least once a day is a good idea in my book, but after that it is a big waste of steam.

The current plan is a more heavy duty belt and pulleys. The drive ratio is not going to be quite as aggressive as it was this time. Right now it is 1:3.43. I'm thinking between 1:2 and 1:3 is probably what I'd be happy with. It would be very interesting to have a variable transmission or a gearbox with a few options right now. :) But I have a feeling that you would just find your favorite and stick with it.

What broke: L Series Timing Belt, Trade No. 660L100, trapezoid 1" width, 0.375" pitch, neoprene,

Thinking of this replacing it with this:
High-Strength HTD Timing Belt
Gates PowerGrip GT3
Width 50 mm
Length: 2m Curved Teeth
Pitch: 8 mm
Material: Neoprene
Reinforcement Material: Fiberglass
Trade No. 2000-8m-50
SL Ethel wrote:Please keep the updates coming. It's been great getting to watch your boat come to life.
Thanks are much appreciated! Glad it's entertaining. :)

-CB
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DetroiTug
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Re: Nyitra I

Post by DetroiTug » Thu May 25, 2017 9:23 pm

HTD 50 mm / 1.968" width really seems overkill. That would probably handle a hundred horsepower.

Go to Stock drive products/Sterling instrument and they do or did anyway, have a PDF that lists the characteristics of each belt by width etc. The HTD series is much stronger than the L series belts. I retrofit CNC machines and use both L series and HTD belt types. An HTD 15mm/590" width belt has a very high break failure strength ( around 1600 pounds if I remember correctly) , they handle a 2 hp servo with no issues at all. I only use L series when it's an old Bandit or Boss control as that is what Bridgeport used and the original machine pulleys are used for the retro. If it's all new I use HTD. The poly belts if you can get them are stronger, they are typically steel (high tensile cables) lined. The rubber belts are glass lined. HTD 15mm width will handle 3-4 horsepower no problem, but I think they are rated much higher than that. Why your belt broke, who knows, probably got damaged somehow or something went in between the belt and the pulley, the inertia broke it. CNC Bridgeports use L series 3/4" width. 1" width should be overkill for your app. That is why I suggested a while back about putting a cage of expanded metal around it. They are great transmission devices under normal operation, but won't tolerate much abuse. Easily cut and break when they are in a considerable bind.

-Ron
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cyberbadger
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Re: Nyitra I

Post by cyberbadger » Thu May 25, 2017 11:42 pm

Ron thanks for the input. I'm going to back down to 30mm. John Winn is using a 30mm belt successfully on a steam launch - but I don't think his belt is in the water, not sure.

I'm wondering if all the water rushing past and the belt turning faster is the problem. I have thought about making a well that's just for the propeller shaft end with the pulley and the belt. That way I could eliminate the water's interaction, as well as any debris in the water. Keeping that well water tight though seems like a pain (I would be creating a bilge on a boat that doesn't really have a bilge).

The machinist who did the propeller shaft taper for me said he had some concern for the water getting caught between the belt and the pulley and having no where to go. He suggested he could machine holes in the pulley so the water had somewhere to go.

Really wish I new exactly what was going on when the L belt snapped, but I don't. :) So I have to guess at my solution.

I do like what I see about the HTD pulleys that they accept different grades of belt so I could start with something reasonable and then upgrade to a stronger belt if need be.

-CB
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dampfspieler
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Re: Nyitra I

Post by dampfspieler » Fri May 26, 2017 7:14 pm

Hi,

have you the belt covered? You shold run your engine more fast and change the beltratio to 1:2.

Best Dietrich
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cyberbadger
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Re: Nyitra I

Post by cyberbadger » Fri May 26, 2017 7:31 pm

dampfspieler wrote:Hi, have you the belt covered?
Nope. Right now it's goes from the deck down into the water and the pulley on the propeller shaft.

-CB
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cyberbadger
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Re: Nyitra I

Post by cyberbadger » Tue May 30, 2017 12:47 am

Very dissatisfied with the first paint. Checked in 2 months.

Different paint - Majic Farm and Implement Exterior Oil - Ford Blue.


New 30mm wide ss HTD Pulleys, and HTD Gate PowerGrip3 belt to be delivered tomorrow.

-CB
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cyberbadger
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Re: Nyitra I

Post by cyberbadger » Fri Jun 09, 2017 4:10 am

You don't even need steam to get hurt....

I'm going to loose a thumbnail because my thumb got thwacked into the bronze 18" diam prop on Nyitra while using a rubber mallet on the propeller shaft.

Hurts like heck, I've been soaking it in ice water. It's got a blue area. :cry:

-CB
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Re: Nyitra I

Post by TahoeSteam » Fri Jun 09, 2017 5:09 pm

mmm that's pretty uncomfortable!
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cyberbadger
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Re: Nyitra I

Post by cyberbadger » Tue Jun 20, 2017 2:04 am

So after some though to the belt brakage I'm making what I'm calling a "belt bilge". This is a 3"x5" 3/16 thick structural aluminum box extrusion. It will house the bottom HTD pulley drive pulley on the propellor shaft and the part of the belt below the deck.

So part of it is a semi/experiment. I don't mind if this "belt bilge" is full of water at full stop up to a knot or two. At that point is should start to drain from 1/4" pipe on the bottom. I think the belt being in the water at slow speeds is fine. It's when you try to go over say 2 knots that the belt becomes significantly inefficient and is hit by shear forces from the volume of water. I have an elbow and check valve that will be connected to the part below. It should drain like any boat at speed when you take the stern plug out? If not I can plug it, and try to drain the belt bilge manually with a hand pump.

So - you have to understand - I consider myself very hack at machining. I do have a benchtop grizzly mill and a benchtop grizzly lathe, but I am not very good at machining. This part I just finished for me made me happy that it turned out so well!

Milled edge off of 3/4" thick aluminum stock to within reasonable tolerances for my purposes to be a loose fit into the square hole that it plugs.
4x 1/4-20 drilled and tapped
1x 1/4 NPT drilled and tapped

Image

Image

Image

-CB
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cyberbadger
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Re: Nyitra I

Post by cyberbadger » Wed Jun 21, 2017 1:58 am

So for now I'm going to put the belt bilge concept on hold, due to crew availability and the strong desire to get back on the water.

Installed the new HTD 30mm wide pulleys and belt tonight with my buddy Istvan so we can test tomorrow.

-CB
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