Radial Arm Saw Upgrades (B&D 7740/3421 Type 3)

[stephan wintner]

Hello,

I have an old RAS, a B&D 7740/3421 Type 3. I am looking to upgrade it, especially regarding the safety guards, but also the table. The saw itself seems to be in solid shape, striaght, square, no excessive play in the bearings.

Searches turned up a few ideas:
- return spring to keep the head from wandering about (I can cobble something up)
- modern blade guard (ideally like the sears upgrades, but how ???)
- fence and tabletop with Kreg or similar tracks, which would permit
fingerboards for ripping
a stop
hold-downs for cross-cutting

I am not sure how to approach adding tracks, while still staying clear of the blade during miter cuts. I may have to use a top suitable for cross and rip cuts only, to which I could clamp a sacrificial layer for mitering. Alternately maybe I will just set the tracks below the table.

And I have not found any "modern" guards which can be retrofitted. Any ideas ? Should I just order the sears guard and see if I can persuade it to fit ?

(I intend to use it for a variety of rough and medium quality cuts, nothing crazy precise. Rabetting will be done on a router or hand plane. I may cut simple dadoes but doubt it.)

Thanks in advance
Stephan

[Charlie Velasquez]

stephan wintner said:

I have an old RAS, a B&D 7740/3421 Type 3. I am looking to upgrade it, especially regarding the safety guards, but also the table. The saw itself seems to be in solid shape, striaght, square, no excessive play in the bearings.

There should be NO play in the bearings. If you are talking arbor/motor bearings, they are easily replaced. If you are talking roller head bearings, they can be cleaned and then adjusted to remove play.

Searches turned up a few ideas:
- return spring to keep the head from wandering about (I can cobble something up)

You will adjust the roller head bearings so as to need about 5-6 lbs of force to move the yoke (lift 3 quarts of water.. should feel about like that when you pull the yoke). This will address any wandering.

- modern blade guard (ideally like the sears upgrades, but how ???)

The stock guards that came with the 7740 are adequate. The saw is confined via the yoke to a cast iron channel. It pretty much will only go where the arm is pointing. The guard really doesn't do much.

- fence and tabletop with Kreg or similar tracks, which would permit
fingerboards for ripping
Your fence is consumable. For crosscuts it helps to identify the exact entry point of the blade and provides support for wood fibers to help reduce tearout. Eventually the kerf gets slightly wider, so you slide the fence over to make a clean kerf after every few jobs
For rips you may want to switch the fence for something longer and taller, and without any kerfs, I use a melamine shelving fence about 5 feet long and 6 inches higher than the table. The extra length helps guide the piece and the higher fence allows you to clamp featherboards to it. Featherboards can also be clamped to the table. they need to be modified some. Because they are clamped at the edge of the table, maybe 17" away, you need to account for the extra torque/leverage they will have. The featherboards need to be longer, maybe 20-24 inches and you will need to either incorporate another clamping location in your featherboard design (almost like a "Y" shaped board) or more simply, butt another another board 90* to your featherboard and clamp that down.

a stop
hold-downs for cross-cutting

I am not sure how to approach adding tracks, while still staying clear of the blade during miter cuts. I may have to use a top suitable for cross and rip cuts only, to which I could clamp a sacrificial layer for mitering. Alternately maybe I will just set the tracks below the table.

Do a search for a "Mr. Sawdust Table"

And I have not found any "modern" guards which can be retrofitted. Any ideas ?
Should I just order the sears guard and see if I can persuade it to fit ?
See above

(I intend to use it for a variety of rough and medium quality cuts, nothing crazy precise.

Buy or borrow a copy of Jon Eakes' book, Fine Tuning Your Radial Arm Saw. Currently out of print, but you can download it as a pdf from his website. Your saw will be precise
Because it can do so much, RAS have an abnormal number of adjustments. Get this book and do them right to make the saw precise and safe.

Rabetting will be done on a router or hand plane. I may cut simple dadoes but doubt it.)

Thanks in advance


The 7740 is the baby brother of the bigger saws, but, if well tuned and a good quality sharp blade (low or negative hook is not a bad idea) , a very capable machine. It was my only saw for about 25 years. Even after getting my unisaw, my 7740 saw more use. I finally gave it to my BIL as I upgraded to a 7790.

PS. Welcome to the Creek!

[Roy Turbett]

Charlie hit on just about everything. I built aluminum t-tracks into my "Mr Sawdust" table and cover them with a 1/2" MDF sacrificial top. I use the t-track for hold-downs and featherboards. As for the fence, I do what Charlie describes. I also moved the fence release from the back of the saw to the front by adding some cams. Here is a link to a write-up I did.

[stephan wintner]

Charlie, Roy, thanks for the comments.

Something like Roys table is what I was thinking. I should have clarified - I am aware the fence is consumable for cross-cutting and mitering. I was thinking of a secondary fence/track carrier which would clamp to the consumable fence. Or as Charlie suggested, just plain a separate rip fence with featherboard. But maybe I can go with just tracks in the tabletop.

The main reason I wanted a "modern" guard was to contain the chips - right now they get thrown at me when ripping. If I adjust the guard downward till they are not, then I cannot see anything. Maybe I will just add a piece of clear polycarb as a chip deflector....

Thanks much, I need to think more but this is what I was looking for. (Further comments welcome)
Stephan