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Aluminum T-Slot Build Using Misumi Extrusion
I debated in which forum to post this, but since Misumi doesn't seem to get a lot of discussion, it seemed warranted to put a build log here to show what their products look like and what the US company can do when ordering almost exclusively over the web.
Note: I am not affiliated with Misumi or Misumi USA in anyway, shape or form. I am merely a satisfied customer.
First-off, the basics:
Machine Type: 2.5D router, primarily for wood
Cutting dimensions: 1400mm x 1000mm x 150mm
Total Footprint (LxWxH): 2310mm x 1290mm x 1400mm
Construction: Aluminum with some steel
Budget: Let's not go there ("around $5k" before software)
The Design
I have read a ton of build threads, bought plans from Joe, and taken copious quantities of notes over about 18 months of planning and procuring. Not to be modest, but I would say that there is absolutely nothing that is interesting or new about my build other than I am using a less well-known supplier for most of my mechanical parts (Misumi). Granted, I've got some high-end parts scavenged via the eBay gods, but the design can be summed up this way: moving gantry, underslung screw drive using ball screws and linear guides. However, since I placed this thread in the T-slot forum, a critical question worth answering: why did I choose Misumi instead of 80/20 or even Bosch, well, that may be an interesting divergence.
I originally started with the idea of using 80/20 and going the typical eBay route for procurement. However, 80/20 does not offer any machining services on its eBay products, so I spent a fair bit of time trying to find good deals on pieces that looked to be about the right size for the machine I wanted (I was/am targeting being able to machine a half-sheet of Baltic Birch plywood - approx. 60"x30").
While scanning eBay for good deals on stuff, I happened to find, in rapid succession, a 1500mm NSK class 5 ballscrew, a Hirata linear actuator with 1000mm of travel, a Parker Daedal linear actuator with 150mm of travel, and two THK SR30 rails that are 2100mm long. This was a big haul of high-end parts for a shade over $1500. Now to keep looking for that aluminum...
I ended up finding a Texas company with a load of Bosch Rexroth 4590 "heavy" extrusions at approximately 7' lengths (really a bit short of that, it turns out). I did some quick sketches to be sure that I knew about how much I would need, and I placed the order, plus I got some gussets for connections and some 45" long lengths to act as posts and stringers. Good so far?
I was on a hunt for a nut bracket housing when my Google skills led me to Misumi's website. I did not find a ball nut housing that was compatible with my NSK screw, but I did find a promotion for 30% off your first order up to $150. Figuring that I knew a decent deal when I found it, I ordered up some of the pieces that would require greater precision than I was really capable of producing with a table saw, circ saw and a drill driver, and I waited for delivery.
Since this post is getting long and is short on pictures, let me cut to the chase on the Bosch: being unwilling to use my table saw to cut the aluminum meant that I made a hash of several of my pieces of stock. Given the quality of what I was getting from Misumi, I shifted my focus to procuring from Misumi and selling my Bosch Rexroth extrusion after the build was done. Now let's have some pictures of that mess (be gentle).
One thing of note in the first picture: I bought the "H" or heavy Bosch Rexroth 4590 extrusion. It is made from 6063-T6 aluminum and weighs 4.15kg per meter. The two Misumi pieces in the picture are Misumi's GFS extrusion, which is 6061-T6 aluminum, and they weigh 5.22kg/meter, or about 25% more than the Bosch ones. If you bought both new, the Misumi extrusion would also be a few dollars cheaper per meter than the Bosch. Misumi's "standard" extrusion, the HFS series, weighs 4.14kg per meter, or basically the same as Bosch's "Heavy" extrusions, and they use 6005-t5 aluminum (similar to what 80/20 uses).
Here are some thoughts from ALCOA on 6063-T6 vs. 6005-T5 and 6105-T5:
http://www.alcoa.com/adip/catalog/pd...y_60056105.pdf
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Bringing the Gantry Together
My first order from Misumi was a bunch of GFS8-4590 (the HEAVY kind) chopped up into little pieces to make up my gantry. Lots of people go with a heavy beam of some sort for the main structure of the gantry (the 3" x 6" 80/20 extrusion is popular) since the support arms of the gantry need to clear the cutting area of the Y-axis fully.
For me, I am starting with a Hirata MB-202AP, which is essentially a 20-10 ground ball screw, linear guides, a mounting table and a motor mount all wrapped in a heavy aluminum extrusion. Because I don't think this was the version designed specifically for mounting vertically, I added an extra reinforcing extrusion on the back. The rest of the frame, then, looks a lot like a chair or a lower case "b".
What I like about the Misumi extrusion and machining service is that I can specify cuts to 0.5mm and get tolerances to 0.2mm (with an upcharge, of course!). When using the "blind joints", this stuff comes together very, very tight. There is no play in any direction with just a few of the screws tightened up. Seriously, I had to use a mallet to move the center support bars into position.
Also visible in the photos are the extrusions I am using to adapt the Y-axis table so that it will mate with the Z-axis table ("dipping" style Z-axis). More on that later.
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Misumi Deflection Calculator
With only one commenter, I'm not sure anyone else is really reading this thread. However, search might eventually lead someone to it. As a result, here is a down-and-dirty deflection calculator I worked up in Excel. It is only focused on the "8-45" extrusions from Misumi that have been of interest to me. These are the larger structural extrusions with a 10mm wide slot, targeted to work with M8 screws. These can get to be pretty beefy (e.g., the 100mm x 200mm extrusion is over 20kg/meter), so if you need bigger, I want pictures of what it is you are building.
Note 1: I did cross-check the results I was getting for the HFS series extrusions versus the calculator I have from Bosch for its 45 heavy series extrusions. The results closely correlate as one would expect when the materials and geometry are similar and they are within 10g/meter of the same weight.
Note 2: For improved accuracy, one would want to model the deflection inherent in the beam under its own weight as well as the deflection that results directly from the load (inherent deflection will be a continuous load, evenly distributed). I did not do that, so these numbers will be a touch optimistic for deflection.
For those looking for Imperial/English measurements, I invite you to research the CONVERT function in Excel. Since basically everything I've been dealing with has been metric, I am doing all of my design and build in metric.