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Oct 22, 2012, 05:27 AM
Registered User
Gary Cee's Avatar
Yes , 1 1/2 times the diameter is the rule of thumb . The thread pitch and material hardness are other factors . Fine threads in soft materials do not hold as well as coarse threads . If the thread pitch is 0.5 MM , 6 threads would be 3 mm . Rules of thumb , like thumbs are often broken. There is little need for a lot of tension on the backplate cover so this is not a maximum clamping force application .
Studs rather than screws at any rate are a safer bet as they square up better and allow full thread purchase. . If you are using a bushing , by the time you allow for an inside and an outside thread it would seem that just using a larger screw could be a better option . If the screw in use is a 3 MM , the 3.5 mm screw or even a 6-32 could be an option as they are smaller than 4 MM .
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Oct 22, 2012, 09:07 AM
Dieselized User
gkamysz's Avatar
As long as the clearance hole for a 4mm screw leaves enough material on the lug of the backplate, that's the easiest way to go.

Greg
Oct 22, 2012, 09:21 AM
Registered User
Gary Cee's Avatar
Quote:
Originally Posted by gkamysz
As long as the clearance hole for a 4mm screw leaves enough material on the lug of the backplate, that's the easiest way to go.

Greg
Of course,
The 3.5 MM and 6-32 were given as options in the event the 4 MM (preferred) was too large . However , a 4 MM threaded bushing would not have sufficient meat to adequately accept a 3 MM internal thread .
Oct 22, 2012, 09:24 AM
Hope to get out of life alive
kenh3497's Avatar
Quote:
Originally Posted by gkamysz
As long as the clearance hole for a 4mm screw leaves enough material on the lug of the backplate, that's the easiest way to go.

Greg
I'll look at that tonight when I get home. In my mind right now it seems that lug on the back plate is not very big. If I do go the bushing route I would be able to keep all the screws the same size. I hate it when I need a different tool for one out of four bolts. I would like the repair to look "professional" instead of a cobbled up repair. Not that a larger screw would looked cobbled, it just doesn't match.

Ken
Oct 22, 2012, 11:52 AM
Registered User
Reginald's Avatar
Quote:
Originally Posted by gkamysz
I would use a helical thread insert.

Greg
That's what I suggested, safest way. Or send the casting to Clarence Lee if you do'nt want to risk your engine.
Oct 22, 2012, 08:28 PM
ProBro, 3D
gregory.da's Avatar
delete
Last edited by gregory.da; Oct 28, 2012 at 11:58 AM.
Oct 22, 2012, 08:42 PM
Registered User
williame3590's Avatar
I just bought this model, video is from John the previous owner.

Saito 300 on C&H
Saito 300 on CH Ignition and 1/3rd Sopwith Pup Assembly (12 min 7 sec)


Bill
Oct 23, 2012, 06:23 AM
I HATE GLOW PLUGS!
SrTelemaster's Avatar
Quote:
Originally Posted by williame3590
I just bought this model, video is from John the previous owner.

Saito 300 on C&H
http://www.youtube.com/watch?v=I9_saL9qVTo

Bill
A 300T on C&H CDI is a dream to operate.

Stay W/a full synthetic oil for best results.
Oct 23, 2012, 09:08 PM
Livin ta fly
sparkx38's Avatar
OK I am glad I found this site dedicated to Saito's. I have a Saito 82 mounted on a tiger 60 upright. I broke it in per the manual and have gotten numerous good flights out of it (a couple of gallons if that much). Then it started back firing and at the time I didn't relize that a rich high end would cause this. I adjusted the valves with the supplied guage and the back firing stopped (best of my memory). Now I cant get it to run up to full RPM by needle adjustment to save my life. Its extremely sloppy on the top end and I cant get it out with the needles. Could it be the Valves I adjusted? So anyway I could use some help getting everything set back to a good starting point. I can't find the valve guage so I geuss I need to know what this should be set at and second a good starting point on the needle settings. And anything else I might be missing or need to consider.
Oct 23, 2012, 09:09 PM
Livin ta fly
sparkx38's Avatar
Quote:
Originally Posted by williame3590
I just bought this model, video is from John the previous owner.

Saito 300 on C&H
http://www.youtube.com/watch?v=I9_saL9qVTo

Bill
Awesome model!
Oct 24, 2012, 08:35 PM
Registered User
Gary Cee's Avatar
Quote:
Originally Posted by Reginald
That's what I suggested, safest way. Or send the casting to Clarence Lee if you do'nt want to risk your engine.
Yes,understood. A Helicoil will still be a 4 mm OD,depending on pitchh. A bushing much larger than 4mm. The options are limited by space at times.
Oct 24, 2012, 08:45 PM
Livin ta fly
sparkx38's Avatar
Hmmmm thought this forum would be a little more helpfull!
Oct 24, 2012, 09:03 PM
Dieselized User
gkamysz's Avatar
Sometimes people are busy. Idle needle is flush with the throttle arm and the main 2.5turns out for basic setting. If you can't turn in the main needle enough to lean the engine it's possible the needle seat or needle are damaged. Valve clearance is .0015-.004". The manual is on the Horizon site for the product if you've lost yours.

Greg
Oct 24, 2012, 09:03 PM
ProBro, 3D
gregory.da's Avatar
delete
Last edited by gregory.da; Oct 28, 2012 at 11:59 AM.
Oct 24, 2012, 09:10 PM
Livin ta fly
sparkx38's Avatar
Quote:
Originally Posted by gkamysz
Sometimes people are busy. Idle needle is flush with the throttle arm and the main 2.5turns out for basic setting. If you can't turn in the main needle enough to lean the engine it's possible the needle seat or needle are damaged. Valve clearance is .0015-.004". The manual is on the Horizon site for the product if you've lost yours.

Greg
Sorry! Didn't mean to sound pushy or rude. How can you tell if the needle or seat are bad?


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