The Coolidge Chronicles #17: Part 1 - 1952 Delta Multiplex 40-B 12"-14" Radial Arm Saw Rebuild

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Blog entry by darthford posted 01-12-2014 09:08 AM 4254 reads 1 time favorited 8 comments Add to Favorites Watch
« Part 16: Part 2 - Grizzly G4003G Gunsmith's metal lathe 12x36" 2HP - assembly Part 17 of The Coolidge Chronicles series Part 18: Part 2 - 1952 Delta Multiplex 40-B 12"-14" Radial Arm Saw Rebuild »

I picked up this 1952 Delta RAS off craigslist impressed with the amount of cast iron and design for cross cutting long boards. I looked at modern sliding miter saws but saw too many complaints about quality and inconsistency. I need a crosscut saw that cuts straight on the first try every time and if this several hundred pound beast can’t do that nothing can.

Well…rebuilding it turned out to be a LOT more work than I thought. It needed a few hundred dollars worth of work to the motor, bearings, electronic starter, capacitor, and since I was in that far already I went ahead and had the windings soaked and baked and the motor which itself is cast iron sand blasted and painted. I’ll have to paint it over but that’s another story.

Here’s the first pic, doesn’t look too bad from a distance. I thought meh a good cleaning, a few new bearings maybe some paint and I’d be good to go, it wasn’t to be the case.

Lets take a closer look…ugh rust!

And more rust

And the hits just kept coming, that’s one of the 4 nitralloy precision ground rods the carriage bearings ride on doh!

Yes rust just about everywhere

Look at this thing, I had to take measures!

I give you the rust destroyer a product call Evapo-Rust wow it saved my butt on this project. Take a look at the after picture, all I did was soak it over night and rinse with Simple Green under the faucet wow!

It took a while to cycle all the parts through my gallon of Evapo-Rust. What I found was Delta assembled this saw ‘then’ painted it so every bare metal internal surface wasn’t protected and has been rusting the last 61 years. I elected to tape off the contact surfaces and paint every last remaining surface to avoid this happening again, underside of the castings included. Here’s a group shot from tonight, I’m about ready to begin re-assembly.

Here’s a close up


V-grooved and ready for aluminum brazing

The Bernzomatic aluminum brazing rods worked quite well.

I elected to leave a bit more of the brazing material for strength vs grinding it perfectly flat. This will be painted black in any case.

There is a 2nd internal 1-1/2 inch arbor nut on the motor, I finally found a socket big enough but the OD was too big so I chucked it in the new metal lathe and presto!

That’s it for part 1. Just about everything is painted now and I have all the new parts in, carriage bearings, needle bearings, thrust bearings, 4 hardened precision ground 1/4” rods for the carriage ways and a new gear. There was one internal component with a gear that was broken and I’m going to have to machine a new one on the lathe.

8 comments so far

View stefang's profile


15881 posts in 3363 days

#1 posted 01-12-2014 11:17 AM

You are a brave man to take on such a big renovation and it looks like it is going very well. I expect you will have an A1 machine when it’s finished. It will be nice to see how it performs. I’ve heard so much pro and con about RAS machines that it leaves me confused about how good they really are. Some say they aren’t accurate enough while others claim they are better and more flexible than miter saws. I imagine the difference must be how they are adjusted and used. I remember my brother talking about them, back in 1950 I think it was, about how innovative and wonderful they were.

-- Mike, an American living in Norway.

View Handtooler's profile


1580 posts in 2161 days

#2 posted 01-12-2014 12:02 PM

WOW! You’ve really brought that beast back to almost manufactured new condition. That’s a FANTASTIC job. You surely are a wonderful machinist to tackle something of that magnitude. So, that new monster of a lathe has already seen some necessary use. Many thanks for sharing.

-- Russell Pitner Hixson, TN 37343

View Picklehead's profile


1041 posts in 1958 days

#3 posted 01-12-2014 12:58 PM

Fine work.

-- You've got to be smarter than the tree.

View darthford's profile


610 posts in 1953 days

#4 posted 01-12-2014 06:48 PM

Stefang – while researching and shopping for a RAS it seems the saw designs got progressively cheaper and less accurate over time. When Sears and Montgomery Wards jumped into the market to sell to the masses my guess is that Delta and DeWalt had to cheapen their designs to compete. Delta only made my saw in 1952, they revamped the design vs 1951 and changed it again in 1953.

1953 and later Delta RAS smaller fixed turret to angle the saw for miter cuts.

My 1952 RAS has a large turret that can also be adjusted front to back on cast iron ways. So I have a cast iron top arm, a 7 inch diameter cast iron plate that rides on the top arm ways and another 7 inch diameter cast iron plate that bolts to the carriage track. Everything can be locked into place and with surfaces that large there is less issues with rigidity and maintaining accuracy. Base cast iron, column cast iron, the more cast iron the better imo. Later RAS have bent sheet metal bases far less robust components and more aluminum.

View darthford's profile


610 posts in 1953 days

#5 posted 01-12-2014 06:57 PM

Handtooler the new lathe has been quite useful so far. Today I’m going to start with a giant 3/4 grade 5 bolt I got at the hardware store and see if I can make a replacement for this broken piece. Not only are several teeth broken off this thing its bent. I purchased the gear from McMaster Carr and plan to braze that piece on.

This component is just a micro adjust wheel to position the assembly on the cast iron top arm. I don’t really need it, its only useful if you plant to turn the saw 90 degrees to rip wood sideways which I’ll never do, I’ll lock it in place for optimal cross cutting and leave it there. But it bugs me that its broken. lol

View stefang's profile


15881 posts in 3363 days

#6 posted 01-13-2014 11:00 AM

Thanks for that history lesson Darthford. It puts the little I know about these saws into perspective.

-- Mike, an American living in Norway.

View hjt's profile


850 posts in 3167 days

#7 posted 01-19-2014 06:35 PM

Wow! just saw this. I’ll have to check it out further… after the game (championship Sunday.) Do you know about the RAS forum at Delphi? You have to sign up to get in, but no cost. It’s all RAS – all Day.

-- Harold

View darthford's profile


610 posts in 1953 days

#8 posted 01-19-2014 07:45 PM

Thanks for the link Harold, I signed up but it looks like the forum is primarily about DeWalt and I have a Rockwell/Delta so I probably can’t post stuff about my saw over there but no matter its still a cool forum I’ll check it out.

Save your ‘wow’ for part 5 its going to be epic, I have been re-assembling the saw today and its going together nicely.

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