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As I started getting serious about building this machine I reread build logs of larger format machines. The experiences of building my first machine taught me that I wanted a floor standing machine - not one that would move about the top of my workbench. My first sketches on paper was simply a scaled up version of my first machine - then I saw "Arbo's" build log (see CNCZone thread # 88276) and suddenly the light switch went on - my design came together pretty much over night.
As I continued to think about the design and read, I came across LunchTrayRider's very nice build (thread #96416) and was motivated to move forward as I saw his rapid progress.
As recommended by others, drawing the design in 3D helps find issues before construction begins. I used SketchUp to model my ideas and I highly recommend doing this. I found several problems in my design caused by tight clearances that I wouldn't have found until construction was underway.
I've attached a rendering of my SketchUp design. Note, you'll see that the design has changed since I drew this - but this was a very useful exercise.
With my design much more robust I had the makings of a shopping list. I could reuse some of the components from machine #1 but due to the increase in size I switched from Acme screws to a Ahren's Rack & Pinion system. I want to recognize and publicly thank Ahren (www.cncrouterparts.com) and Nate (www.finelineautomation.com) for being truly helpful to this community by providing helpful information through numerous posts, and selling at reasonable prices the parts needed to realize the dream many have of building their own robot minion. After sending emails and getting useful responses I ordered rails, racks, motors, and R&P kits from Nate. I subsequently ordered a new power supply and cables directly from Ahren's site too.
I made it almost a daily ritual to see the 8020 Garage Sale store on eBay (stores.ebay.com/8020-Inc-Garage-Saleto) see if they had newly listed 3030 extrusions available. I really lucked out one day back in January - a listing that had 3030 sized extrusions 60" long with Anchor Fastener Counterbores (the very strong connection). A few days later another listing shows up - 34" pieces with Anchor Fasteners as well (for the legs of the machine). The guys and girls at 8020 are fantastic. Every order I've made has been packed and shipped professionally and quickly. I don't know how much aluminum they ship but they get really good prices from UPS - even for the packages that weigh in at over 75 pounds and approach 72" in length). There is a lot of good advice about using carriage bolts and drilling access holes in the 8020 parts on CNCZone. I made the decision to use mostly 8020 nuts including the Anchor Fasteners - especially after I bought some slightly used parts at a very steep discount. If the extrusions didn't have the holes bored for the anchors I would have followed the lower cost route. As it is, the anchors work very, very well.
8020 makes a metric size extrusion (the 40 series) that I wrongly thought was simply the fractional size but marketed to metric customers. Don't make the same mistake I did - the parts are NOT interchangeable! I mistakenly bought some 40 series 45 degree supports that I had included in my design. When I tried to assemble them they did not fit. I made an on-the-fly decision to do without the extra supports - we'll see if it comes back to haunt me.
My first machine used a Bosch palm router. I like it. It is robust if a little noisy. My only complaint was the 1/4" shank limit for router bits. As I followed the trials and successes of others moving from routers to spindles I decided that I too would take a chance and buy directly from China. I bought a 2.2KW spindle from Love-HappyShopping and the transaction was painless. Delivery was made within 1 week including DHL having to drive over 50 miles one-way twice because they couldn't find the road that I live on. Like a kid on his birthday I opened the box excitedly. My first reaction was "Wow, this is a lot heavier than my Bosch." It seems well made and looks like it was tested before being packed for shipment (a little water dripped out when I flipped it upside down).
With the new spindle I needed to buy a new bracket. I found David Da Costa's site in a post (www.spindlemounts.com) and contacted him about a custom mount. David is a great guy who does very good work. I drew a sketch of my idea and David turned it into a professional drawing and confirmed everything was as I needed. He built a custom backplate to my specification and shipped it out very quickly. Of course, there is an old saying -- measure twice, cut once that I ignored. When I tried to mount the custom backplate to my linear slide, I realized I gave David the wrong measurements. With embarrassment fully justified I asked David to create me a second custom backplate. He turned it around in a day! Talk about great service. I highly recommend David.
One of the lessons from machine #1 was dust control is not optional. I saw the video of Kent Jane's split dust shoe (thread 97533>) and liked the simplicity and the refined design the video showed. I contacted Kent and asked if he made the dust shoe that would fit the 80mm diameter of the Chinese spindle - he does! So, I ordered one and when it came it was packaged better than most massed produced items - the brushes and dust chute were protected from being crushed with plenty of recyclable packing material. You need dust collection - if you don't have a dust shoe - please consider buying one from Kent.
More photos of building to follow!
