Battleship Wally

Battleship Wally

Postby smooshed » Sun Dec 08, 2013 8:10 pm

We are calling our Wally-To-Be "Battleship Wally", because we intend to make the frame from 1/2" aluminum plate. These parts were printed for us by sgraber, I think they turned out great.

Questions and comments about assembly coming soon!


IMG_1708-1.jpg
Plastic Parts
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Re: Battleship Wally

Postby smooshed » Tue Dec 10, 2013 8:34 pm

I've finished mounting the bearings. Turns out I didn't have to heat the parts. I'm glad, because thinking about melting Wally parts made me nervous.

Our parts were close enough that all I had to do was take care of some high spots - - - -

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Printing Artifacts
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------- and some flash. I started by using a small half round file -------

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Arm and File
IMG_1711-1.jpg (56.77 KiB) Viewed 51159 times


-- and once I had a handle on what needed to be done I moved on with a dremel. The dremel needs a *very* light touch, but all is good.

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Re: Battleship Wally

Postby owens-bill » Wed Dec 11, 2013 6:24 pm

Nicholas will tell you that I was extremely skeptical of the oven heating trick when assembling the GUS prototype, but I'm convinced - it really does work. I prefer the hair dryer to the oven, though, both for finer control and keeping the heating concentrated on the area that needs it.
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Re: Battleship Wally

Postby smooshed » Wed Dec 11, 2013 7:01 pm

My backup plan was a heat gun. I have a "hobby" one that is meant for shrinking model airplane covering, I think it would have worked well. Then there is our industrial one, Master Appliance brand, lowest temp is 200F, some models go up to 1000F. It would make quick work of PLA :-) Really, though, there was very little to do before the bearings would just "pop" in.
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Re: Battleship Wally

Postby Cozmicray » Thu Dec 12, 2013 1:05 am

I just used big screw, washers and nut
heating bearing helps with tight ones

Wally_Bearing_Press_2.jpg
pressing in bearing on Wally arm
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Re: Battleship Wally

Postby Ralphxyz » Thu Dec 12, 2013 4:19 pm

Freeze the bearing!! That is what machine shops do!!

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Re: Battleship Wally

Postby Nicholas Seward » Thu Dec 12, 2013 5:24 pm

I would suggest freezing the bearing if it was an interference fit with ductile and/or strong enough metal. The plastic is low strength and fairly brittle. What I like about using heat to get the bearing into its socket is that it relaxes the part.
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Re: Battleship Wally

Postby Cozmicray » Thu Dec 12, 2013 5:44 pm

This is NOT metal - metal issue

Heating the bearing just heats the polymer up
a bit, evenly to expand hole a bit.

Heating bearing gives even heat up around polymer hole
expanding it for a bit to get bearing in.

The bearing outside is spherical so you get it by max diameter
of sphere.

:D
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Re: Battleship Wally

Postby smooshed » Sun Dec 22, 2013 2:56 pm

One of my compadres at Speco was busy inventing problems for our Wally build, and pointed out something interesting. It seems that if there is any variation in the length of the arms for the Z axis mechanism, "interesting" things will happen to the bed as it moves up and down.

So, I got curious, and wanted to see where we stood with respect to arm length variation -

IMG_1722_1.jpg
Measuring across pins
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Turns out that I was able to find four arms that measured to within .001" of each other! I didn't expect that, but it means that at least for us there is no problem :-) . Bearing alignment is very good too, most of them are dead nuts on (technical term), a few are a little stiff. This was done with .314 pins, .315 was no-go.

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Re: Battleship Wally

Postby smooshed » Fri Jan 17, 2014 2:11 pm

We're finally making some progress ! At least, we're simulating making some progress :)

Before we put a new job in one of the machining centers, Orlando, our part programming guru, runs a simulation of the g code to verify it. The simulation includes a high fidelity model of the machine tool, including fixtures. If there is a bug in the code, much better to crash into a simulated fixture than a real one.

This is the first operation for Battleship Wally's backboard.

Last edited by smooshed on Mon Jan 27, 2014 1:56 pm, edited 1 time in total.
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