Tuesday, February 19, 2008

Band Saw Nirvana

My newest garage addition arrived Friday afternoon. A while back I went shopping for a bandsaw to cut metal, since I do a fair amount of fabrication for my cars. I ended up purchasing an older 12" Craftsman band saw off eBay. It's a pretty neat design--the table remains flat and the entire bandsaw head tilts up to 45 degrees to make bevel cuts. Even better, it has a DRO (Digital Read Out) for blade angle, speed, and tension. I ordered some nice expensive bi-metal saw blades from MSC Industrial and thought it was the cat's meow.

That was about two years ago. Fast forward to about a month ago, when I started preparing for some more metal fabrication projects on my 2G Talon. Even though the saw cut metal pretty well, it was clear that it was cutting too fast. When cutting aluminum, the blade would get so hot that the aluminum would fuse to the blade and occasionally even seize! I had never truly investigated blade speeds for metal cutting saws; instead, I had taken the seller's word that it was "metal cutting". The slowest blade speed on the Craftsman is 1500fpm. Recommended blade speed for my applications are ~90fpm (stainless steel) and ~300fpm (aluminum). Clearly there was a problem here!

I started by pulling apart the bandsaw to see if I could slow it down via resized pulleys. Some simple math made it clear very quickly that I would need multiple sets of pulleys to gear the bandsaw slow enough for metal cutting. This would require a fair amount of expense and effort to do, with no guarantee that I'd end up with what I wanted in the end. To paraphrase a quote from Top Gun, I decided it was better to retire the saw and get a new one than push a bad position...

Any sane person with my budget would have probably just headed over to Harbor Freight for their 4x6 bandsaw (so named for its cutting capacity of 4" x 6"), on sale at the time for $160. This same saw can be had under many different brandnames from numerous sources, but they all use the same castings as far as I can tell and are basically the exact same saw with very minor changes (different motor, slightly different base, nothing significant). We have one of these saws at my workplace; and despite the fact that it's the most inexpensive bandsaw available, I am of the opinion that it's an overpriced POS.

I briefly toyed with the idea of buying a portable bandsaw, as used on construction sites. I found this Vertikut accessory that would allow one to turn a Milwaukee portable band saw into a vertical metal cutting saw (which I thought I preferred over a horizontal saw--more on that in a bit). Milwaukee also sells an accessory to turn the saw into a horizontal cutting saw, but it uses a chain pipe vise--not ideal for the varied cuts that I expect to be doing. In the end, it would end up costing a pretty penny to go this route, and once again I felt I would be pushing a bad position.

At this point, my problem was that a "good" bandsaw that had all the features I desired was at least 3-4x as expensive as the 4x6 HF version. As much as I love having good tools, I couldn't convince myself that it would be worth spending that much money. In my research I found that there is a subculture of garage machinists out there, some of whom have taken the time to put together some very nice pages detailing 4x6 bandsaw mods (also one here and another one here). Problem is, I want to spend my time on my car, not tweaking a saw! (Ask my wife how easily I get sidetracked...)

I was just about to suck it up and head over to HF to pick up a 4x6 saw when I received an email that made things very interesting. A few days earlier I had found a very nice (albeit somewhat large) saw on eBay at a low price with zero bids. I emailed the seller to request a freight quote--why not, right? Well, his response came hours before the end of the auction, and no one had bid on the saw yet. Adding the two numbers together, the price was very appealing and well below anything I had seen on Craigslist, HF, and eBay. I quickly started researching this particular bandsaw, and I liked what I saw. So, I got an OK from my incredibly understanding and supportive wife, and I bid on this saw--and won! Final price including freight was several hundred below the lowest price I could find on the web without freight, and less than half the price that most places are asking. I think I got a pretty good deal!

The timing couldn't have been more perfect. I was preparing to list my bandsaw on craigslist at a significant loss. I mentioned this to a coworker that sits two cubes away, and he seemed interested in the saw. Sure enough, he picked it up a few days later. I gave him a good price, and I'm happy to know it's going to a good home. Even better, I now had space in my garage for the new saw! Thanks to good Q2 FY08 performance, my employer gave me a half-day last Friday. I arranged for an afternoon delivery with the freight company. We had a going-away party for a couple of my coworkers, so I was a bit late getting home. I almost missed the delivery, as the driver was preparing to drive away! Needless to say, I tipped him for the inconvenience.

Here it is, in all its glory:

For those who care, it's a Clarke Power Products 7in. band saw (model BT1025). As the photo shows, it's a horizontal saw (although I've noticed it has provisions for mounting a simple baseplate for vertical saw use like on the 4x6 saw). It has a hydraulic downfeed, which is probably my favorite feature. Unlike the hokey spring tension downfeed adjustment on the 4x6 saw, the hydraulic downfeed allows me to precisely adjust how quickly the saw head "falls" and hence the pressure on the saw blade at the cutting interface via a small knob on the side of a hydraulic cylinder. The saw also has a coolant pump with drip tray, flexible spray head, and bucket reservoir. I haven't cut with coolant before, but I'm excited to have it--heat is definitely the enemy when it comes to cutting metal.

I spent an hour or so aligning the saw and setting it up to make straight cuts, and here are the results of the first few cuts:

The "smeared" cut on the far right was from the Craftsman, in contrast with the other cuts from the new saw. These cuts are a bit rough, most likely due to the relatively coarse 8tpi pitch of the blade that came on the saw, but they're as square as the carpenter's square that I used to set up the saw (i.e. the best I can measure). A few quick passes on the sander will quickly clean up and deburr the edge. I never made cuts this square with the Craftsman vertical saw, even using a guide--they always required refinishing after I made the cut, and occasionally I had to start all over because the part ended up underdimensioned. The Clarke's blade is a whopping 3/4" wide, which certainly helps make the cuts straighter. It's also a bi-metal blade instead of a cheap carbon steel blade like the one that comes with the HF 4x6, so it ought to last a very long time.

Overall, I'm really psyched about my new saw, and I'm looking forward to creating some great new stuff with it!