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Mikado valve gear screws

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  • Member since
    April 2017
  • From: Australia
  • 46 posts
Mikado valve gear screws
Posted by SAR 500 on Friday, December 8, 2017 8:19 PM

Well back into the athearn usra mikado 2-8-2 overhaul and doing practice on the pick a apart loco, anyways I come to disassemble the valvegear and I noticed the main grub srew (see photo) is a bit stubborn to get out, try as I might to get it out no good,have a change of screwdriver size no good, in the end I had to drill it out with the pin-vise and a couple of differnt size drill bits.

I'm not happy having to do this but it was the only way unfortunatley a couple of the donor mikes have tight grubs screws and I don't have spares.

So to all  the locomotive repair and service men and women could you pleas point me in the direction of where to get a 1mm diameter by 5mm long grub screws please so I can complete this overhaul and the overhauls to come

https://www.flickr.com/photos/141527269@N07/27148182489/in/dateposted-friend/

https://www.flickr.com/photos/141527269@N07/25053169208/in/dateposted-friend/

 

Thankyou

Cam

 

 

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Posted by maxman on Friday, December 8, 2017 11:03 PM

I don't know metric, but would it be something like this: http://www.mrmetric.com/M31525

?

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Posted by 7j43k on Friday, December 8, 2017 11:44 PM

Cam

I'm a bit confused.  In the first photo, it appears you might be talking about a setscrew.  In the second, a headed screw.

So, if we (I) are to help, a bit more precision is necessary:

 

please, using a micrometer, accurately measure the overall diameter of the screw in question.

is it headless, or does it have a head?

what is the length?

 

All that said/questioned, have you considered calling Athearn and asking for help with the screw replacement?  I have spoken to them, and found them to be quite helpful.  Or:  they try to be, which is about all one can ask.

 

Ed

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Posted by doctorwayne on Saturday, December 9, 2017 12:52 AM

SAR 500
Well back into the athearn usra mikado 2-8-2 overhaul and doing practice on the pick a apart loco...

Other than for practice, why would you disassemble the valve gear?
The mechanism on those locos is very smooth running, and none of mine have ever had an issue with the valve gear or siderods, despite use on heavy trains.

NorthWest Short Line has various styles of metric fasteners, and should have something that will work.

Wayne

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Posted by SAR 500 on Saturday, December 9, 2017 1:36 AM

maxman

I don't know metric, but would it be something like this: http://www.mrmetric.com/M31525

?

 

 

Right kind of style just a slotted head and 1mm shorter but spot on otherwise

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  • From: Australia
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Posted by SAR 500 on Saturday, December 9, 2017 1:55 AM

7j43k

Cam

I'm a bit confused.  In the first photo, it appears you might be talking about a setscrew.  In the second, a headed screw.

So, if we (I) are to help, a bit more precision is necessary:

 

please, using a micrometer, accurately measure the overall diameter of the screw in question.

is it headless, or does it have a head?

what is the length?

 

All that said/questioned, have you considered calling Athearn and asking for help with the screw replacement?  I have spoken to them, and found them to be quite helpful.  Or:  they try to be, which is about all one can ask.

 

Ed

 

Ed

https://www.flickr.com/photos/141527269@N07/38042903595/in/dateposted-friend/

https://www.flickr.com/photos/141527269@N07/27152547599/in/dateposted-friend/

Its the screw out of the boss head on the third driving wheel of the mike where all the rods meet, it not headless either I know them as a cheese knob head locally here but its all I know it as.

dimentions done with calipers (don't have micrometer just yet.... will be put on the shopping list for the next visit to the tool shop, I knew I had a funny feeling I should have bought them last timeSad ) in mm's first

length 5mm

head diameter 1.71mm

thread diameter 1.15

 

in Inchs

Length 0.197

head diameter 0.067

thread diameter 0.045

their is a little 5to the right of those figure

 

As to athearn the though hadn't crossed my mind

 

 

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Posted by SAR 500 on Saturday, December 9, 2017 2:09 AM

doctorwayne

 

 
SAR 500
Well back into the athearn usra mikado 2-8-2 overhaul and doing practice on the pick a apart loco...

 

Other than for practice, why would you disassemble the valve gear?

 

Ah well unless there's another way to remove and replace a split gear on the Athearn usra mike and put the NWSL one in its place without dropping the wheelset then I'm none the wiser.

But as far as I know you disassemble the valve gear drop the set of wheels with the split gear, pull one wheel off the axle. remove gear and put the NWSl in and reverse the process.

Or is thier another way to go about the process  as I know no different on this oneConfusedEmbarrassed

 

Any ideas on how to go about would be apprecaited I need a little help on this one.

 

Thankyou

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Posted by maxman on Saturday, December 9, 2017 8:13 AM

7j43k
In the first photo, it appears you might be talking about a setscrew.

I believe it looks like that because he is showing the screw after he started drilling out the head.

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Posted by rrebell on Saturday, December 9, 2017 8:49 AM

You can modify a screw as to length and smaller head.

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Posted by 7j43k on Saturday, December 9, 2017 9:56 AM

Cam,

 

From your numbers, it sounds like you want an M1.2 x 5mm (cheese head) screw.  I see one here, among other options:

 

https://www.amazon.com/Stainless-Machine-Slotted-Threaded-M1-2-0-25/dp/B00DD4FCTO/ref=sr_1_4?ie=UTF8&qid=1512834711&sr=8-4&keywords=m1.2+5mm

 

"cheese head", huh?  I have heard of "fillister head", but not that.  And yet cheese head is what shows up on the link.  

So, in theory, you've got your screw.  Well, 10 of them.

 

Ed

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    April 2017
  • From: Australia
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Posted by SAR 500 on Saturday, December 9, 2017 12:07 PM

maxman

 

 
7j43k
In the first photo, it appears you might be talking about a setscrew.

 

I believe it looks like that because he is showing the screw after he started drilling out the head.

 

 

Its actaully before I drill it out, I cannot get enough light on the screw in the rods so it does look like I have started drilling and shows a lot of shadow

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Posted by 7j43k on Saturday, December 9, 2017 12:38 PM

SAR 500

...I noticed the main grub srew (see photo) is a bit stubborn to get out...

 

 

 

A grub screw is a set screw, which has no head.  On consideration, I believe you are talking about the crankpin screw on the main driver.  This would account for the photos of a loose screw with a (cheese)head.

Is that perhaps correct?

Some confusion could have arisen because there is, I believe, a set (grub) screw in evidence in the first photo of the locomotive.  There appears to be such a thing used to attach the eccentric crank to the crankpin.

Anyway, as I noted earlier, there appears to be a source for the screw you are searching for.  And for a variety of other sizes, if necessary. 

Ed

  • Member since
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  • From: Australia
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Posted by SAR 500 on Saturday, December 9, 2017 12:56 PM

7j43k

Cam,

 

From your numbers, it sounds like you want an M1.2 x 5mm (cheese head) screw.  I see one here, among other options:

 

https://www.amazon.com/Stainless-Machine-Slotted-Threaded-M1-2-0-25/dp/B00DD4FCTO/ref=sr_1_4?ie=UTF8&qid=1512834711&sr=8-4&keywords=m1.2+5mm

 

"cheese head", huh?  I have heard of "fillister head", but not that.  And yet cheese head is what shows up on the link.  

So, in theory, you've got your screw.  Well, 10 of them.

 

Ed

 

 

Yes that's one and a packet ordered now, havnt heard of them called that but now I have.

Thankyou ED

  • Member since
    April 2017
  • From: Australia
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Posted by SAR 500 on Saturday, December 9, 2017 12:59 PM

7j43k

 

 
SAR 500

...I noticed the main grub srew (see photo) is a bit stubborn to get out...

 

 

 

 

 

A grub screw is a set screw, which has no head.  On consideration, I believe you are talking about the crankpin screw on the main driver.  This would account for the photos of a loose screw with a (cheese)head.

Is that perhaps correct?

Some confusion could have arisen because there is, I believe, a set (grub) screw in evidence in the first photo of the locomotive.  There appears to be such a thing used to attach the eccentric crank to the crankpin.

Anyway, as I noted earlier, there appears to be a source for the screw you are searching for.  And for a variety of other sizes, if necessary. 

Ed

 

Yes it is the one in the crankpins and one or two mikes have stubborn ones that dont want to budge either, I should know my screws better fancy calling a cheese head a grub screwOops - Sign the ol eyes are playing tricks

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Posted by doctorwayne on Sunday, December 10, 2017 1:09 AM

SAR 500
doctorwayne SAR 500 Well back into the athearn usra mikado 2-8-2 overhaul and doing practice on the pick a apart loco... Other than for practice, why would you disassemble the valve gear? Ah well unless there's another way to remove and replace a split gear on the Athearn usra mike and put the NWSL one in its place without dropping the wheelset then I'm none the wiser....

Okay, good point.  I've got six of those Athearn Mikes, but never a problem with the gears, so I've never really looked at how that eccentric crank is attached.

On most steam locomotives, there's a setscrew which is loosened, then the crank can be removed, along with the main- and siderods.  The geared axle is then dropped, without further disassembly of the valve gear.

Wayne

  • Member since
    April 2017
  • From: Australia
  • 46 posts
Posted by SAR 500 on Saturday, December 16, 2017 7:34 PM
Thankyou Wayne

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