VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #241  
Old 01-14-2020, 07:58 AM
DanH's Avatar
DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 8,950
Default

Quote:
Originally Posted by rwtalbot View Post
How are you attaching the gear to the shaft? Loctite 638 might be an option with interference fit, or is there still room for a grub screw? There must be a secure solution involving a minimum of machining. It looks like Dan may have used grub screws.
No grub screws for me. Both the trigger wheel and the bearing collar are a light press fit locked with ASME B18.8.2 split pins in double shear, 0.125"D.

The idea was to create a cartridge, a complete shaft assembly for insertion into the body. It is retained with a surface plate, rather than the internal snap ring chosen by Colin. An internal ring requires installing the trigger wheel after the fact.







All dimensions are nominal. Detail all bearing fits. Trigger wheel is a KSS1-36 from from qtcgears.com.

Usual caution; experimental, use at your own risk.
__________________
Dan Horton
RV-8 SS
Barrett IO-390

Last edited by DanH : 01-14-2020 at 08:03 AM.
Reply With Quote
  #242  
Old 01-14-2020, 02:04 PM
WingsOnWheels WingsOnWheels is offline
 
Join Date: Mar 2009
Location: Plano, TX
Posts: 1,808
Default

Quote:
Originally Posted by rwtalbot View Post
Interesting, so you have an O-ring seal at the top or is that grove for bearing retention?

How are you attaching the gear to the shaft? Loctite 638 might be an option with interference fit, or is there still room for a grub screw? There must be a secure solution involving a minimum of machining. It looks like Dan may have used grub screws.
The groove at the top of mine is for a snap ring to retain the bearing.

The spacer between the bearings is retained to the shaft by a dog-type grub screw. The tip of the screw has an unthreaded portion that fits into a matching hole on the shaft. The tip extends about 3/8' into the shaft and is 3/16 diameter of grade 12.9.

The top gear is held on in a similar fashion. However, since my gear position lined up perfectly with the existing rivet holes in the shaft (from where the magneto was cast on) that pin passes all the way through the shaft. There is also a regular grub-screw on the gear as well. I just left that since there was already a second threaded hole from the gear manufacturer, so why not. According to the spec for Grade 12.9, that little 3/16 dog should have a shear strength close to 19k pound.

In my case, the bottom bearing is pressed in. and everything else is assembled on top of that.
__________________
Colin P.
RV-6A #20603
Complete 5/10/19
PP SEL / A&P
I donate every year on my B-Day (in Dec), but donated early in Sep'19.

Last edited by WingsOnWheels : 01-14-2020 at 02:07 PM.
Reply With Quote
  #243  
Old 01-14-2020, 05:16 PM
DanH's Avatar
DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 8,950
Default

Had a private note with a very good suggestion. The trigger body could have an oil weep hole to vent the bearing space. It would offer an early indication of oil seal failure. Although oil is unlikely to bother the magnetic pickup, oil washing is not good thing for sealed bearings.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Reply With Quote
  #244  
Old 01-15-2020, 06:56 PM
WingsOnWheels WingsOnWheels is offline
 
Join Date: Mar 2009
Location: Plano, TX
Posts: 1,808
Default

I have one, wasn't planned for that purpose. It is and access point for the dog in the center bearing spacer, just in case. At least I was smart enough to align it with the timing, so I can stick an allen wrench in there snd it will hold the gear properly aligned with the pickup.
__________________
Colin P.
RV-6A #20603
Complete 5/10/19
PP SEL / A&P
I donate every year on my B-Day (in Dec), but donated early in Sep'19.
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 07:54 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.