Unboxing Day

Remember in my last post when I so hopefully said it would be "later today" when we met up, opened the box from Misumi, and divvied up the goodies?  Well, that was before my wacky work schedule and Tony's even wackier work schedule came into play.

So... on the afternoon of Saturday, 08 June 2013 the stars did finally align and I found myself at Tony's place to open the box.

Now, before we go much further here, I must apologize for my lack of skill with a camera.  Some of the photos to follow are a bit blurry.  Hopefully (there's that word again), as we go forward, my ability with the camera will improve.

This is a shot of Tony's Prusa Mendel printer, showing how he uses a plain bed covered with blue painter's tape as a substrate for his printed items.  The can of hairspray in the background is used as a sort of "tacking agent" to help the first layer stay flat on the bed.  The extra extruder gears are early rejects his daughter (she's two and cute as she can be) attached to various random points.  The little grey figure at left atop the left-hand Z Axis leadscrew dances around as the printer operates, much to her delight.

Next we see a shot of the box from Misumi just prior to opening.  I was surprised by how small the package was.

  

 

 That's a laptop in the background with about a 17" display, just for reference.

As can be seen here, Misumi sure packed the box with plenty of protection.  I was really impressed with the care and precision with which this shipment was put together.

With the big wad o' plastic removed, we can see the extrusion pieces neatly wrapped together with stretch wrap.  These folks weren't taking any chances.  Note also the bubble-wrap in the bottom.

  

There was this awful feeling I'd had for the two weeks since the box arrived that maybe I'd gotten the part number wrong and the extrusions would arrive without the center hole shown in the CAD drawing.  I'm glad to report those fears were totally unfounded.  The center hole goes the entire length of the extrusion, making tapping it for M5 a whole lot easier.

 

Finally, here's a shot of the Sanguinololu controller at the heart of Tony's Prusa.  We will likely be using this same setup on both our MendelMax builds, as it is very well integrated, inexpensive, and has proven to be quite reliable so far in service on the Prusa.

It's going to take me a while to finish up on the Master BOM, and it's beginning to look as though McMaster-Carr will get the order for fasteners when I'm done.

I'll also be ordering the spiral point M5 tap and tap handle from them, so once the order is received the real fun of the build will commence.  Now, where'd I put my try square and level? 

Next time, we will be covering the assembly of the lower frame elements.        

Organizing a Bill of Materials

Tony and I should meet up and open the box from Misumi later today.  Hopefully, I'll have more to post on that later on.

Meanwhile, I've been going through the MTW Build Guide with a fine tooth comb, trying to sort through the Parts Overview and create a rational Bill of Materials for our builds.  I'm finding the organization of the existing parts lists/BOM to be somewhat, um, disorderly.  There is little consideration given to the sequence in which these parts need to be ordered, which I believe is because the Build Guide is geared to the MTW MendelMax kits.  There are also very few actual supplier part numbers given, nor, for that matter, is a list of suppliers evident in any detail.

Since it is my aim to source as many parts as I can myself and only buy kit parts for what I can't find or make myself, my BOM (in its final form) will be organized a bit differently to permit taking advantage of economies of scale and quantity purchasing to contain build cost.

Just as an example of how a well-organized BOM can make a difference, take the case of M5 X 10 mm SHCS (Socket Head Cap Screws).  These are used in many different areas of the build, and knowing how many are needed for all phases of the build, one may buy them in bulk from a low-cost supplier to get a better deal.  

 Pricing from several sources, I have so far found a better price for these in quantities per 100 than I have in smaller quantities.  This quantity jibes well with the number needed for the build, too.  I have been as yet unable to find a local supplier who keeps these on the shelf in large quantities, and so will have to order and have them shipped, adding to the cost of purchase.

There are significant variations in price for M5 x 10 mm SHCS at different suppliers.  The highest price I found per 100 is about $30, while the lowest is nearer $9, and I'm not done looking, because every penny off the unit price of a fastener at this quantity saves a dollar on the total cost.   Prices of fasteners, in particular, can have a real force-multiplying effect on the cost of a build if not researched carefully prior to purchase.

As assembly phases are completed, I will be posting the relevant as-built BOMs.  Then, after the printer is fully assembled and in debug phase, an as-built Master BOM will be published.  Why am I waiting until I have an as-built?  This is to prevent my mistakes from becoming yours.  I'll talk about mistakes made and pitfalls encountered along the way plenty in this blog, but not in the BOM.  That document is intended to become an accurate reference for this build, and to be useful to anyone who might be following along.

It is my intent to use a numbering system for items which organizes parts in order of build phases, and further by function.  It goes something like XXX-XXX where the first group is an assembly group, and the last is the item number in that group.  A partial list of assembly group numbers might run like this:

000 - Common Parts/Fasteners - used in nearly all phases.
          010 - Fasteners
          020 - Printed Plastic Parts
          090 - Calibration & Debug Common Parts
100 - Frame Components - used in constructing the Frame
          110 - Specialty Fasteners for Frame Assembly
          120 - Frame Assembly Printed Parts
          180 - Aluminum Extrusion Frame Members
          190 - Frame Debug & Calibration 
200 - Y-Axis
          210 - Y-Axis Specialty Hardware
          220 - Y-Axis Printed Parts
          230 - Y-Axis Drive Components.
          290 - Y-Axis Debug and Calibration

Note the skip between 120 and 180, 230 and 290.  There's room in there for other functional groups as needed.  A lot of this will be echoed in further Assembly Groups, e.g., something ending in "20" will always be a Printed Part.  

Yeah... I'm somewhat of a detail freak for stuff like this.

Boring stuff until you need to know what's used when and where.  I'll develop this more as we go along, integrating it into the as-built BOMs.  Meanwhile, I hope to have some photos of the Misumi unboxing in the next entry.  

Ciao for Now!