65 replies to this topic

[Ben Morrow]

Help! On the picture below, do I line the comm tabs to the timing marks in degrees or do I use the small slits between the comm segments to get a trure reading? 
 
I'm asking because I've seen a few pictures on "How to" and some show other ways that just don't match what's shown below.

Thanks!  

[zipper]

Slits - some measure the center of the slits, some the leading edge, also depends on the measuring device. Mine has a needle that goes into the slit.

[havlicek]

What Pekka said! 

On modern comms, the slits between comm segments are generally narrower than on the older coms such as the Kirkwoods, so the "pointer" of your timing device probably doesn't have any "wiggle room." so measuring either the center or the leading edge of the slits is kind of besides the point in most cases. Quoted timing advance numbers aren't usually all that accurate from what I've seen anyway.

There are electronic/digital timing devices that may be much more accurate than a "protractor and pointer" type device, but I don't have any experience with them, nor would I know any way to verify the numbers they generate other than... a "protractor and pointer" device!    On a regular protractor type device, the longer the pointer, the more accurate it will be... IF... the pointer is dead-straight and the armature is resting on a very flat surface

[Ben Morrow]

Thanks guys,  I'm working on a new gauge to check/set timming with and will post pictures soon, IF the dang doctors will leave me alone a while.  

[MSwiss]

I'll just add that comm tabs have zero to do with the timing.

 

On some comms, depending on their use with a particular type of arm, and resulting timing range, they might be offset, for convenience of use.

[havlicek]

I'll just add that comm tabs have zero to do with the timing.

 

On some comms, depending on their use with a particular type of arm, and resulting timing range, they might be offset, for convenience of use.

 

Oh boy is this one important.  Sometimes, coms can have a "built-in-advance", which is really just that the tabs are offset from the center of the com segments.  ***If you are using the tabs for some reason as a way to spot timing, this can lead to some really nasty surprises, especially because these can be offset in such a way as to produce a CW timing advance (*the opposite of the way most all coms today are advanced).  I'm not sure if it's only the Tradeship coms, but those are the only ones I've seen with this "feature", but it's important to check for, and both their 2mm and 36D shaft size coms could be had this way.  ***You can still advance the com in the opposite direction, but it will make the tab position a real nuisance when winding.  ALWAYS use only the com slits for timing and not the tabs just to be sure.  I don't know of a timing gauge that uses the tabs as a reference, but I guess some might use the tabs to refer to "by eye" or even make a home-made fixture that references the tabs, but the slits is what counts and they're dead-easy to use anyway.

[Ben Morrow]

Slits - some measure the center of the slits, some the leading edge, also depends on the measuring device. Mine has a needle that goes into the slit.

 

 

Zipper,

The one I made fits in the slit also. Just a spring steel wire with a point on the back side of the bushing. 2mm hole for arm w/ a tiny hole drilled beside it and steel wire soldered in place with very sharp point on the com side, works great THANKS! That little rig and a protractor should do the job.?? 

 

Mike,

I've never seen a com with advance built in. I do understand how it would work just never seen one. Have a pic. ??

 

John, I got you buddy!

 

Thanks guys!

[MSwiss]

Mike,
I've never seen a com with advance built in. I do understand how it would work just never seen one. Have a pic. ??

First of all, again, the tab has nothing to do with the timing.
 
To be clear, where it is, is irrelevant to the timing.
 
Here's a couple Koford arms.
 
An X12 and a C12 where the comm was never trued.
 
They are clearly not anywhere in the middle, between the comm slots.
 
Where it makes the most sense is in the C12 arm, where offset location allows the comm welding to be done in the well, away from the coils.
 
It also allows the comm tabs to be pushed back, for more clearance, with the inside of the endbell.

 

 

 

 
 

[Ben Morrow]

Mike,

Not using the tabs for timming, just want see what a advanced com looked like. Everyone has made it very clear to use the slits..

 

Ben 

[MSwiss]

I'm just trying to get you to use a different term.

 

What I showed are not pictures of an "advanced comm".

 

They are comms with offset tabs.

 

You're welcome for me taking the time to post 3 pics.

[Ben Morrow]

Here's some pics, guys,

 

#1 My home made winding rig

 

#2 3 and 4  pointer I made.

 

# 5, 6 Timing marks and confusion. check the degrees on the paper scale, then the protractor scale.

 

Still not real sure on which is correct. Need help here folks. The arm states and marked 40 degrees but no matter what I do I can't get a 40 reading.

 

Help me learn here, what's wrong here???

 

Feel free to hate on the pink towel, it's all the wife would give up!  

 

Ben

 

 

 

 

 

 

 

 

[Ben Morrow]

I'm just trying to get you to use a different term.

 

What I showed are not pictures of an "advanced comm".

 

They are comms with offset tabs.

 

You're welcome for me taking the time to post 3 pics.

 

Mike,

 

Thank you for your time and posting the pics.

 

Ben

[MSwiss]

And thanks to you.

 

Nice job on your timing gauge.

 

Don't get hung up on perfection.

 

You just need a repeatable reference.

[Bill from NH]

Ben, when the arm sits on the pink towel (or something else) is your arm shaft perpendicular to the protractor face? i ask because, I have a similar plexiglass timing gauge that came with a lucite wedge for keeping different diameter arms perpendiculat to the gauge's face.

[Ben Morrow]

Hi Bill,

 

Yes, sir! The arm is sitting flat against the protractor and the protractor is straight up and down. The arm shaft hole is sitting perfect. Well not so well on the pink towel but yes on a good flat surface.

[Ben Morrow]

Guys,

 

If anyone would like to share what device they use for timing I think this would be a big help in my quest for setting the timing.

Even better if shown with the arm showing the setting! This would be greatly appreciated..

 

Ben 

[zipper]

Pah - you copied my design... And the factory measures almost never hit the point. A batch Koford Gr 27 37 deg arms measured between 35 and 41, Pro Slot 45 deg measured up to 52 deg, etc.

[havlicek]

A quick google search under "protractor timing gauge" yielded this and other images:

 

Note that the pointer/indicator is long enough to reach the full height of the gauge. That should give the most accurate reading.  The one I use is basically the same, although it was screenprinted and sold for slot car armature timing. Any protractor will work, as long as the shaft hole is a good (and not too sloppy) fit for a shaft.

[zipper]

I have the shaft hole drilled through a glass mirror (the scale is on the back side) with a dentist's diamond – no play there so far.

[Ben Morrow]

Guys,

 

Thanks for the posts and pics! It's my wife's birthday and I need to stay out of trouble!   Mothers Day and birthday heck I'll be in trouble in NY skimit! 

 

I shall return!!! Later...   

[Phil Smith]

This might work OK. I just ordered one. 

Westcott Protractor Ruler, 6", 15cm, Transparent

[Bill from NH]

It will depend upon where you drill a 2mm hole for the arm shaft and how you intend to keep everything level. From the pictures, the distance from the protractor's bottom edge to the point where all the angles start, appears to be less than an arm's diameter. Maybe not?

[Ben Morrow]

Note that the pointer/indicator is long enough to reach the full height of the gauge.  That should give the most accurate reading.  The one I use is basically the same, although it was screen printed that it was sold for slot car armature timing.  Any protractor will work, as long as the shaft hole is a good (*and not too sloppy) fit for a shaft.

 

I think this is the way I'll be going. Picked up a nice new protractor today and wiil use the pointer I made up shown above.

 

Note: In the picture John posted above it shows the pointer going to the right side of the scale with the comm sitting against the scale.

With the comm. against the scale (as shown) it looks to me that after setting the timing the arm would be advanced 30* when the arm. is installed in the can. In other words, looking at the can end of the motor the motor would be spinning in a CW direction and advanced 30 degrees.

 

Is this what you guys are seeing? If so I think this is the method I'll be using please let me know if my thinking is correct or all wrong!

[Ben Morrow]

It will depend upon where you drill a 2mm hole for the arm shaft and how you intend to keep everything level. From the pictures, the distance from the protractor's bottom edge to the point where all the angles start, appears to be less than an arm's diameter. Maybe not?

 

Yes sir, Bill, That hole will have to be perfect! I'll be setting that up with a tiny punch and 2mm drill bit, then another 2mm motor bushing to keep the hole from getting all sloppy. I kinda feel like I'm now getting close to a good timing gauge if folks agree with whats posted above? 

 

Thanks very much for your input and help on this project!

[Ben Morrow]

Pah - you copied my design... And the factory measures almost never hit the point.A batch Koford Gr 27 37 deg arms measured between 35 and 41, ProSlot 45 deg measured up to 52 deg etc.

 

Zipper,

 

I've checked I'll guess 30 arms and there were I think three that were within 1 or 2 drgree as to what was marked on the stacks! The others, way off... It does seem like the winders could do better. I'm sure in many cases it's pretty dang important to be on the money, like when building Pro or Nats race motors. I'm sure it's important for the racer to recheck for himself after a purchase, but I don't think it can be changed??? For Koford arms that seems odd to me for the quailty and price paid. I'm kind of shocked on that!