Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548
Posted: 09:14pm 24 Feb 2008
Copy link to clipboard
Print this post
Hello Crew,, been working on a new geared timing belt drive shaft ,lately. I've fitted a motorcycle disc brake for easy shut down in storms-we get a few through here,100+ Kph .
The shaft is 32mm and will have the hub at one end for the blades and the other end will carry the disc and gear wheel,, will try a 3:1 ratio at firts,,big 13-14 foot mill should have plety of grunt to over come any friction,he hopes ..
the drive train for the F&P dual set-up will be opposite to sort of balance the weight on the tower -main yaw bearing will be 90mm pipe greased and revolving on a similar ring below ,welded to the stub pipe that will be bolted to the tower steel. I'll angle back the blades to get around 600mm clearence.
Bruce
Edited by brucedownunder2 2008-02-26Bushboy
imsmooth Senior Member Joined: 07/02/2008 Location: United StatesPosts: 214
Posted: 11:59pm 24 Feb 2008
Copy link to clipboard
Print this post
I see you have the neos on the F&P rotor. Is there anything you did to prevent warping of the rotor from the increased magnet strength? What is the thickness and N-number of the magnets?
brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548
Posted: 01:43am 25 Feb 2008
Copy link to clipboard
Print this post
The neo's are some that Matt from Victoria got me ,,he describes how he fitted them in a post a year or so back -search for "Matt" -
The warping,,I've not experienced any real problems with that ,although I remember I had to lightly grind that yellow one back in a few spots. nothing serious,just took a shaving off here and there--It's not affected it ,as it's still as powerfull .. Just hope this new one turns out the same .
the size ,,well each row has 4 small magnets 2 end to end and another layer on top--
some guys got into trouble because they used pvc sticky tape to form the "dam" for the polyester--it just crinkles up ,,the cloth backed Gaffa tape is more tolerant to the heat ..
I've a couple of 1/4 inch thick Alu disc's that could be fastened to the rear of the rotors,,the're on stand-by.
BruceBushboy
imsmooth Senior Member Joined: 07/02/2008 Location: United StatesPosts: 214
Posted: 02:15pm 25 Feb 2008
Copy link to clipboard
Print this post
Will using wax paper for cooking provide a good smooth surface for the damming? I was then going to hold it in place with duct or painter's tape.
brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548
Posted: 08:33pm 25 Feb 2008
Copy link to clipboard
Print this post
Hi IM, if you use wax paper ,how are u going to make it stick to the magnets???
duct tape or painters tape will crinkle with the heat of the polyester going off.---trust me ,,been there,,done that !!!.
the gaffa tape I use has a cloth backing and seems to stick very well and is strong in all directions ,holding the polyester firmly.
BruceBushboy
Jon Bennett Newbie Joined: 01/11/2007 Location: AustraliaPosts: 27
Posted: 02:42am 26 Feb 2008
Copy link to clipboard
Print this post
Looks good,how are you going to activate the brake?
regards
jon
imsmooth Senior Member Joined: 07/02/2008 Location: United StatesPosts: 214
Posted: 04:19am 26 Feb 2008
Copy link to clipboard
Print this post
I was going to use duct tape to fasten the wax paper on the bottom to the rotor. I would leave some of the plastic rotor showing so the tape would go over the wax paper and plastic. The wax paper would just be the inside lining to provide a smooth, non-stick surface.
MyCattMaxx Newbie Joined: 24/02/2008 Location: United StatesPosts: 8
Posted: 03:12pm 26 Feb 2008
Copy link to clipboard
Print this post
If the heat tears up standard duct tape it will surely melt the wax on the wax paper and you will have the paper adhered to the resin. MHO
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 10:18pm 26 Feb 2008
Copy link to clipboard
Print this post
Hi im,
The polyester resin issue.
The polyester contains styrene. This is the main culprit for the tape problems. The heat that is produced increases with the age of the resin and the amount of catalyst used. Fresh resin needs less catalyst and produces less heat. I have experience with polyester in the swimming pool and boat industries, and it seems that from the descriptions that the quantity of resin required compared to the thermal mass of the rotor with magnets would suggest old resin is a problem.
Pre packaged tinned quantities are usually not as good as buying a small quantity directly from a swimming pool manulacturer.
There is an inherant danger with Neo magnets and excessive temperature. Possible magnet degradation can occur due to localized excessive heating of the resin. It is not much good replacing the ferrite magnets, if the replacements become degraded in the process.
I would wrap wet towels around the rotor to keep the temperature down during the resin curing process.
cheers, Gordon.
become more energy aware
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 02:31pm 27 Feb 2008
Copy link to clipboard
Print this post
With all these heat problems I wonder why you folks do not use EPOXY resin? Since I built my 26'wooden boat with that wonderful stuff I am very weary using polyester resins. Yes, they are cheaper but at the expense of a working life of seconds instead of tens of minutes and their heat problem.
Epoxy resin is so much nicer to deal with, it does not have that nauseating smell and it does not attack materials used to contain it (but it may adhere to some!
If I could not use epoxy for some reason, the heating problem of polyester can be minimised by reducing the poured quantity. Doing the job in stages so to speak. To provide a good bond between pours, cut up fibreglass material can be inserted so that some of it gets wetted out by the next pour. Actually, just plain resin (epoxy or polyester) by itself is not very strong, its the embedded glass material that really supplies the strength.
Tinker Klaus
brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548
Posted: 05:38am 14 Feb 2011
Copy link to clipboard
Print this post
I just found this ,, unfinished project incorporating a motor cycle disc brake .
Tried a bicycle type and it worked ok on a smalle mill
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
Print this post
