Crossley Otto Langen

[Craig DeShong]

Better go back to your shop. Didn't you have a lathe in there?....   

Apparently confusion was in my favor.  When those little urchins made their commando raid in my shop they found TWO lathes, not having any clear direction on which to remove,  and since you confiscated their cell phones so they couldn’t get any clear updated directions ,they left with
neither. 

[crueby]

Better go back to your shop. Didn't you have a lathe in there?....   

Apparently confusion was in my favor.  When those little urchins made their commando raid in my shop they found TWO lathes, not having any clear direction on which to remove,  and since you confiscated their cell phones so they couldn’t get any clear updated directions ,they left with
neither. 

 

[Craig DeShong]

Thanks, all of you who stop by to follow this build.

With the rack guide completed, I turned my attention to the rack itself.  After sizing the piece of steel, I spent the better part of the afternoon getting my mill setup to cut the rack.

I used the same procedure I used on the rack of my first Otto Langen, and I still had the jigs and mandrels left over from before.  I make no apologies for this somewhat bizarre setup.  There are probably better ways with different tooling and machinery, but you use what you have and This setup worked before and I had every confidence that it would work again.  I doubt it produces a precision rack with precision teeth; but it will be good enough for my use.

I’m using the right angle drive on my Bridgeport to drive a long mandrel with the involute cutter attached around midway.  On the far end of the mandrel is a ball bearing set in a jig that is clamped to the mill table.  While cutting a tooth, the mandrel rides in the ball bearing; when I index across to the next tooth between cuts by moving the mill table x-axis  , the mandrel slides through the bearing center.  Since I can’t use the Y axis on the mill table to pass the rack material through the cutter (the far end opposite the right angle drive is attached to the mill table) I’m using a little rotary table with X/Y axis movement. Locking the table so it won’t rotate and using the y-axis on that table to pass the work through the cutter head.

This setup produces lots of chatter so going slow is the word.  I get acceptable teeth on the rack when patience and slow going is observed.  Here’s a picture of the setup.


And below is a photo of the business end of things with the first few teeth on the rack cut.

[Brian Rupnow]

Clever set-up. I have thought different times about cutting a rack with my mill, but there is no X-Y feed on my rotary table.---Brian

[Craig DeShong]

Yep Brian; took some head scratching on the first go-round.

Thanks for those of you stopping by to see the progress.  There appears to be quite a few of you, the way the view count keeps climbing.

 
This afternoon was totally occupied with finishing the task of cutting the gear teeth on the rack.  This was slow, tedious going.  Cutting the teeth was only one of the issues; I also needed to make sure nothing was shifting out of alignment.

I don’t have much to show for an afternoon’s work; so I’ll bore you with somewhat redundant pictures.  Here is the setup upon completion of the last tooth cut.



And a closer view of the actual work.



Finally I show you the rack with completed teeth.  I'm very pleased with the result.  The teeth are uniform and of a consistent depth, what more could you want?

Work isn’t done on the rack yet; I still need to cut channels for the rack guide and drill a hole where the rack mounts to the piston.  I’m hoping to get to that tomorrow.

[crueby]

Excellent - thats quite a long rack to cut.
 

[Admiral_dk]

Thanks for those of you stopping by to see the progress.  There appears to be quite a few of you, the way the view count keeps climbing.

I'm one of those who usually reads every post here on the forum and enjoying them all (some a bit more than others). Besides you're doing great on this build so far (we all have hiccups) 

I was wondering about the progress from the first picture of the rack - but I can see that you have moved the clamps on the rack since.

[Kim]

The rack looks very nice Andrew!
I've cut a few gears, but never a rack.  That's something I want to do someday.  Your setup is pretty interesting too!
Kim

[awake]

Great work on the rack! Quick question: what number cutter are you using? In the pictures it looks like the teeth have some of the rounded involute shape, but I always understood that a rack has straight-sided teeth. I doubt it will make a bit of difference in terms of your use of it, but just curious.

Now that I think on it - I believe the last cutter in the set is for some number of teeth up to a rack - as with any gear cutter, it is only the perfect shape for one particular tooth count of gear, but is an acceptable compromise for the others in the listed range. So maybe this is what I'm seeing - a cutter that is optimized for, say, a 100-tooth gear (don't remember the actual number!) but will work okay for a rack ...

[awake]

Excellent - thats quite a long rack to cut.

I suspect it was a nerve-wracking process!

[Craig DeShong]

Chris, Per, Kim, and Andy; thanks for your comments.  Thanks also for those of you not commenting but stopping by to see the progress. 

Per: Yep- As long as you don’t loosen ALL the clamps , things stay in register.

Andy:

I suspect it was a nerve-wracking process!

Yes, making the “rack” was nerve-“wracking”- you did that on purpose, didn’t you?  
Cutter number one cuts a gear having from 135 teeth up to and including a rack.

The day started with profiling the non-business side of the rack to accept the rack guide.  On the full-size a dovetail pocket on the rack mates to a dovetail on the rack guide.




I don’t have any tooling to accomplish that (although no doubt some of you folks could make some) and I went for a simpler approach… though I was back to using some fairly small end-mills again.

With the machining finished, here is a photo of the rack mounted in the rack guide.




And an end-on view to see how things mate.




Now that I’ve side tracked myself away from working in the area of the cast iron platform I made a few posts back, I thought I’d go ahead and complete the piston and get it mounted to the rack and then check the alignment of the rack and rack guide with the piston inserted in the cylinder. 
Here I’m starting to work the piston material down to the required diameter.



With the piston to the correct diameter, I’m cutting the groves for the piston rings.




Then boring out the piston to the required internal diameter.


And with the day waning I called it a day.

<a href="https://www.youtube.com/watch?v=gBzJGckMYO4" target="_blank">http://www.youtube.com/watch?v=gBzJGckMYO4</a>

[Craig DeShong]

Thanks for stopping by to see the latest progress.

Today was a day of running around so I didn’t get much time in the shop.  We’re expecting our first hard freeze here in North Carolina so I needed to stop procrastinating and go get my live steam locomotive

http://www.modelenginemaker.com/index.php/topic,8092.0.html

from the Railroad, bring it home, and prepare it for winter storage.  This involves mostly wiping it down, oiling everything that moves, and blowing residual water out the water lines; then removing the injectors and bringing them inside where they won’t freeze.

That took the majority of the day, but I did finish the piston as you can see below. 

[Roger B]

That's some excellent work on the rack    A very interesting set up   

[Craig DeShong]

Thanks for the compliment Roger; thanks also for those of you stopping by the see the goings-on.

This afternoon I made the bracket that attaches the rack to the piston



And then a shoulder bolt connecting the rack to this bracket that I don’t show. 

With this work completed it was time to assemble the model with piston, rack, and rack guide to see if the rack aligns in the rack guide and the rack and piston moves freely up and down the length of the cylinder without binding.  This was one of the pivotal moments in the build that tell whether you can move forward with the build, or you need to do a lot of re-fitting.  The rack MUST move freely in the rack guide or the engine will not run.

I wasn’t surprised when things didn’t exactly line up.  I needed to shim the rack guide .010 inches at the bottom and .020 inches at the top.  I was expecting to need to shim things a little and this was well within what I was thinking was acceptable.  Even the full size has shim stock to align the rack.  With the shims in place, the rack moves freely up and down; I’m quite pleased.

Below is a photo of the model with the piston at the bottom of the cylinder.   


Ana another with the piston and rack at the extreme top of the stroke (we hope the piston never gets this high in the cylinder).  I have my 6 inch rule in a rack tooth, preventing the rack and piston from plummeting to the bottom of the cylinder.  Without piston rings, without the valve permanently installed, without a sparkplug, and without a gasket sealing the bottom of the cylinder it would freely do so.

[awake]

Excellent! Congrats on getting it all lined up and moving smoothly. You are making great progress!

Andy:

I suspect it was a nerve-wracking process!

Yes, making the “rack” was nerve-“wracking”- you did that on purpose, didn’t you?  

Me?? Surely not!