Allen Models - running boards back in stock

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NP317
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Re: Allen Models - running boards back in stock

Post by NP317 »

Harold said: "One knows, at a glance, if a dimension is critical, or not, and if so, how critical."
That may not be true for the beginning machinist.

Mike's comments on the original Allen drawings are spot on.
When I began to build my Ten Wheeler 20 years ago, I had to carefully study each part, identify the associated dimensions,
and then translate critical ones to decimals with tolerances, after defining what mattered.
The colored notes on my set of Allen drawings tells that story. Basically, I had to redo dimensions to enhance my understanding.

Mike's concept of redrawing the Allen drawings to ANSI standards is an excellent idea. And certainly a non-trivial task.
That would greatly assist new machinists and increase their chances of success, and speed up the progress of experienced machinists.
Critical parts would be defined by specified tolerances on the drawings, eliminating the need for "newbies" to try to figure out what to do!
AND, ANSI-standard drawings make CNC machining much easier to set up, for those with such machine capabilities. And those numbers are increasing.

My thoughts.
~RN
FLtenwheeler
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Re: Allen Models - running boards back in stock

Post by FLtenwheeler »

When I built my 10-Wheeler back in 1982-85 I did not know anything and held everything to plus or minus 0.0005. My engine runs great and I could not be happier with it. Due to the fact that Allen products are so popular with first time builders I would recommend a one page instruction sheet explaining the tolerance of parts. It would have helped me.

Tim
He who dies with the most unfinished projects: Should of put more time into their hobby.
Steve Alley
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Re: Allen Models - running boards back in stock

Post by Steve Alley »

Harold Thank You for your input. You do have a point to a degree.
Mike and I are on board with the changes, but the cost to do so. Also we have found mistakes, customer have pointed out changes needed. So where does one start. We just can not go though every plan set page just to change out fractions to decimals. You may or may not know but the draw #26 for the tender truck is completely new. This is a great example of what we ran into. One new castings patterns from Steve V. and friends that are great by the way. Thank you Steve V. but the new changes were so much on that one print it call for complete new drawing. Saving the old one just in case someone needs it for the old castings.
I have change other patterns too. M199 spoke wheel, new pattern is more rounded then pointed spoke. I am not changing the draw for this, and yes keep the old pattern as is. Some one may brake a flange or need another one and I will be able to supply it for them.

FLtenwheeler Not 100% understanding what you are asking, Yes I agree to what your saying, but how to word it is the question for all to understand and correctly follow. If you like to draft something on this, It would be much appreciated.
NP317 Now here is something that he is correct on. When a casting is matted to another and the other casting is show on another drawing. Gene sometime point this out and then it was omitted on others. We run into this a lot. Example cylinder, cross head, saddle, valve chest, D valve. but here is one you doing see that I do. There is three different drawings for the cylinder itself. American is stand alone, Regular Allen for TW, M, and CO. but even the CO has changes for only it. Now the new 1 3/4" bore 1.750 for 0-4-0, 2-4-0, and maybe by builders chose for the American.
So what I am getting at is so many plans to change but only one at a time. Then to do this thou the years its going to take is asking all to except it as it happens and then one would say, I got my plans 2 years ago and my buddy just bought a set and his have better or changes I want. Can you give me those prints. Answer No but I will sell you those.
So having a spot on the Web site to drop in changes for customer to down load, just those and not the hole print. This is where we are going to start. We also can over load this with to much info. But the most important thing is you all have a say and we want to add to the line to make it better.
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Harold_V
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Re: Allen Models - running boards back in stock

Post by Harold_V »

steamin10 wrote: Sun Jul 15, 2018 6:50 am I have seen beautiful locos literally seize up because of too tight a tolerance for the temperature changes. It is not the fault of the machining. but the fitting.
Correct. Or, said another way, it's an engineering problem, and not related to tolerance, a term that is vastly misunderstood.

Tight tolerance is not the cause of an engine seizing. It isn't because dimensions were held too closely-it's because the wrong dimensions were held. An engineering problem.

Look at it this way. If you design with two thou clearance on a given fit, but then designate a tolerance of ± .003", the overlap will provide a fit anywhere from too tight to assemble to sloppy, assuming one observed the tolerance and ended up on opposite extremes. By sharp contrast, if a dimension is provided that yields a desired fit, but tolerance is restricted to, say, ± .0002", the end result is sure to fit and perform as desired. An engineering problem, not a tolerance problem.

Before a builder can even hope to build a functioning engine, he/she should understand the difference. Tight tolerance isn't a problem, aside from slowing the building process, as tight tolerances require a different work approach, assuming one hopes to hit the dimension reliably.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
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NP317
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Re: Allen Models - running boards back in stock

Post by NP317 »

Harold:
Can you set up a separate discussion on Tolerances or perhaps even better "Allen Models Drawing Updates" and transfer the subjects above to that title?
This is important enough to be a searchable item for future reference.

And it has "polluted" Mikes original note on Allen Runnings Boards now available. Sorry for that Mike.
~RussN
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Harold_V
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Re: Allen Models - running boards back in stock

Post by Harold_V »

NP317 wrote: Sun Jul 15, 2018 9:55 am Harold said: "One knows, at a glance, if a dimension is critical, or not, and if so, how critical."
That may not be true for the beginning machinist.
I admit that the changes to current acceptable practice is a good thing, but what I said is true, doesn't matter the level of competence of the machinist. That's the point I tried to stress. Because NON critical dimensions are expressed as fractions, it's clear that they are open in tolerance. However, if all the dimensions are as fractions, sure, you can't sort which is which, and that's the impression I conjured from reading the comments earlier in this thread. All dimensions, critical or not, were so expressed. Leaving those that don't matter as a fraction eliminates a great deal of the confusion, assuming there's a tolerance block on the print, which was very much a part of the prints from which I learned and machined. At no time did I suggest that leaving all fractions was a good idea. It isn't. I don't express fractions when I do a sketch when building a simple project, but I also know what dimensions are critical (because it's usually my design), so, for me, it doesn't matter. I wouldn't think of giving such a sketch to another, for they would have no way of knowing what I had in mind.
When I began to build my Ten Wheeler 20 years ago, I had to carefully study each part, identify the associated dimensions,
and then translate critical ones to decimals with tolerances, after defining what mattered.
Understood, and that's exactly why what I said has merit. Also, if a guy isn't experienced in building, or machining, he/she may or may not be able to determine which dimensions are critical unless there's a notation on the print. Even then, unless one understands proper fits, knowing that a dimension is critical doesn't provide enough information for a successful decision to be made. If the bore measures 2.250" (specified as 2¼"), how large should the piston be made? Should it, too, be 2.250 (2¼")? The average guy has no clue what constitutes a proper press fit, nor a proper slip fit. For them, it's guess work unless they inquire of others, and even then they're at the mercy of those who respond. I've seen .002" recommended for a press fit for a 3/4" pin, for example. Talk about ruining a guy's day!

My comments were not intended to tell others how to dimension their drawings. What they were intended to do was provide a means for discerning critical from non-critical dimensions, based on a method that used to be standard practice. It helps when EVERYONE is on the same page, and that appears to be the objective of those who are dealing with the Allen products. For that I commend them. It's hard enough to build an engine without having to second guess each and every operation.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
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makinsmoke
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Re: Allen Models - running boards back in stock

Post by makinsmoke »

I have a pair of wheeler running boards unmounted and would be happy to take a photo or two for you.

Brian
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NP317
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Re: Allen Models - running boards back in stock

Post by NP317 »

makinsmoke wrote: Sat Jul 21, 2018 8:38 pm I have a pair of wheeler running boards unmounted and would be happy to take a photo or two for you.

Brian
What are "wheeler" running boards?
'Time to educate Russ some more.
~RN
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makinsmoke
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Re: Allen Models - running boards back in stock

Post by makinsmoke »

Sorry,
Ten Wheeler running boards!!
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