Used tool shopping / inspection

[milanuk]

Well... it looks like I might have a lead on an older Dewalt 12" RAS with cast arm, etc. According to folks on another forum, I should 'run, not walk' and go get it So tomorrow afternoon I'm scheduled to swing by and take a look.

Problem is... I know very little about 'old' machine tools, and I'm not really sure what constitutes 'walk away' and whats minor and fixable. I've heard some mention about worn ways, etc. but not really any description of what I should be looking for.

Any help would be much appreciated.

TIA,

Monte

[Uncle Cracker]

I think with any RAS, one of the most revealing things is how smooth the travel of the saw unit is along the ways... There should be no "hitches or glitches" from one end to the other. The same should go for the elevation, angle and bevel movements. Look also at how clean the motor is, and how smoothly it runs (and runs on after shutdown). There should be no runout or play in the blade arbor (bad bearings if there is). Beyond that, do some test cuts, and use your common sense. Don't want it so bad that you overlook things that will be problematic. Remember also that a RAS is one of the most dangerous tools you can put in your shop, so don't get one unless you're going to run it by the book.

[mpc]

Nothing specific for that tool but some general thoughts:

1: slop in bearings is generally not a big deal... bearings haven't changed in eons and have been standardized for a long time so replacements won't likely be a problem/expensive. As long as it appears you can actually get to them to remove/replace them that is. Often it takes special tools to remove and replace bearings "pressed" onto a shaft. A local automotive machine shop will probably do that job for about $5 to $20 bucks if you bring the pieces to them.

2: stuck bearings, or bearings that rotate poorly: see #1.

3: Bad motor windings, slow motor, etc: this is more of a risk. Most motors can be re-wound (overhauled) by motor repair shops but this often costs a fair bit. Many old tools used motors supplied by a different company - i.e. a more generic motor - so swapping in a new motor is often possible. Finding one with similar bolt patterns and the same size shaft/arbor is the tough part.

4: any busted plastic stuff? That's harder to find for older tools, especially the less common brands.

5: Wire/switch problems: if you're comfortable working with 120 or 240volt wiring, you know this is generally not a big deal. If you're not comfortable with wiring, you'll have to find somebody that can do it for you or do a little reading. Any tool with "electronic controls" though is tougher: those parts tend to be expensive and much more difficult to find. Most of the time the original manufacturer is your only option and not all of them keep inventory for older models. Personally I avoid this stuff whenever possible.

6: slop in the main structure (i.e. play in the sliding part of a radial arm saw): can't help you much here. It may be unrepairable, it may be trivially easy to repair... depends on what is bad and if parts are available again. One thing to consider is an automotive machinist. Those folks can layer fresh metal onto a worn part, then put it into a metal cutting lathe and make it "true" again. Not cheap... but often not terribly expensive.

One thing to look at: eyeball the screws/fasteners. If they look stripped, somebody has hacked at the tool before and it's probably going to be trouble. Rivets? Yikes, a pain to do anything. Beyond that, think about your mechanical skills and what tools you have available... and how much effort you want to put into rehabbing a tool. For me, bearings wouldn't be much of an issue since I have the necessary tools (I do a lot of auto stuff as a hobby) but it may be more than you're comfortable dealing with. If you can eyeball the saw and understand how it works, how the parts go together and what they're supposed to do, then the risks are less. If you look at the mechanical stuff and go "wow" or "why did they do it that way?" then as UC posted "use common sense." Only you know your abilities; I certainly don't.

mpc

[milanuk]

General electrical fix-it stuff I'm okay with, as I have a little bit of background in that dept., although more utility/industrial as opposed to home/consumer stuff. For $100 (or less, if my horse-tradin' skills are up) though I'm not wild about getting too far into a rebuild - I want a functional tool, not another project in and of itself. I'll probably get one or two of the books I've seen recommended on setting up and tuning an RAS - that seems to be the key to getting good, safe results with these tools. Maybe build a new table and/or base for it, and incorporate a workbench to either side to serve as left/right stock support, etc. (eventually) - the idea is/was to set it up primarily as a dedicated cross-cut machine, and keep the 10" SCMS for trim, funky miter cuts, etc.

Hopefully the seller will have it set up somewhat so I can fire it up and test it a little. I've heard that some of these bigger machines like this might be wired for 240v - not a big deal, but I'd have to run a new outlet over to where I plan on sticking it along the long side of the shop.

The boogered screw thing reminds me... thats kind of why I'm a little paranoid about this whole used tool thing. Years ago I ended up fixing some tools that I had been given. Things like finding that the person who had assembled/used the tools (not the person who actually paid for / owned them - long story) had attached the sheet metal stand to the sheet metal housing of a contractor saw with two 2" c-clamps and some 3" long decking screws. They had also ran the bolts attaching the top onto the housing, busted them off (inside the cast iron), and then ran more bolts in - no wonder it wobbled like an out-of balance washing machine when it ran. Thing was, short of crawling under it and then taking it apart piece by piece... I had no idea how 'bad' it really was. I think I'd feel a little awkward doing that in someone else's garage