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Abner
10-05-2018, 08:47 PM
I need a spacer to fit between 2 saw blades on my table saw. I want a 1/8" gap between.
So I need a spacer 2 1/2" in diameter, 5/8" bore, .229" thick.
It need to have contact on the outermost 3/8" of the diameter on both sides, and recessed(?) on both sides.

I have a SB heavy 10 and a bridgeport.

I have watched videos on how to make washers but needing both sides recessed is no something I have found.

How would one go about making such a part?

Thank you in advance!

Beazld
10-05-2018, 09:15 PM
How about making 2 spacers, 1 .229 thick that is 2-1/2” OD X 1-3/4” I D. Make a second one that is 1-3/4 OD X 5/8 ID that is thinner. Make them press fit or use locktite to stick them together. They are just spacers, not subject to axial loads.

Abner
10-05-2018, 09:18 PM
That is clever and far easier for my machining skill level. Thanks!

Toolguy
10-05-2018, 11:03 PM
I would get a piece of 1/4" thick stock and cut a 2-1/2" circle with a hole saw on the mill. Then put it in the lathe chuck and face it to thickness and cut the recess on one side, and true up the OD. You can have the chuck jaws open to about 1/2" and use the live center in the tailstock to hold it against the chuck jaws by the 1/4" hole in the middle. Flip it over and cut the recess on the other side, then clamp it in the chuck and drill or bore the 5/8" hole.

bjmh46
10-06-2018, 05:47 AM
Perfect application for soft jaws if you have them.

Arcane
10-06-2018, 06:53 AM
Is it necessary to have the spacer dished on both sides? I ask because I have seen commercial blade stabilizers without any recess, just plain flat.

MattiJ
10-06-2018, 08:28 AM
I would start from thicker disk cut out of maybe 1/4 plate or dig my washer assortment frantically for suitable stock.

Drill maybbe 3/8 center hole, mount to long extension nut(or hollow bar) with allen head bolt, chuck from extension nut and turn both sides, turn OD and trepann the center hole.
Maybe a bit of overkill but everything is turned with single mounting and you get all the surfaces concentric/parallel/flat without changing to 4-jaw.

cameron
10-06-2018, 09:07 AM
Post#1 seems to imply that you know how to make a plain washer to the necessary degree of accuracy, and are only stymied by the recesses. So make the spacer as a plain washer and chuck in the 3-jaw to cut the recesses. The recesses don't have to be more than a few thou deep, and a bit of eccentricity in the od of the recess and a bit of out-of-parallel condition won't make any difference in the accuracy of spacing or have a significant effect on balance.

michigan doug
10-06-2018, 10:32 AM
If it is really necessary to have both sides recessed a bit, recess one side on the lathe, and then just lightly grind a bit off the center of the second side with a belt sander if you're not confident you can hold it securely to recess the second side on the lathe.

Black Forest
10-06-2018, 10:45 AM
In my farmer logic I would simply drill center hole to size or undersize and ream to size if you think it must be spot on. Then mount on an arbor and turn the outside circumference to size. After that remove it from the arbor and chuck it up in the three jaw and use a boring bar to make your recess on one side and then flip it and do the other side. What have I missed?

mikem
10-06-2018, 10:48 AM
Face off one side and make the recess and then sparingly super glue the finished side to an aluminum round that is chucked in the three jaw. Then finish the other side and snap it off the aluminum round. Would that work?

Abner
10-06-2018, 01:25 PM
I spent the morning welding accessories for my sawmill - 2nd log dog and a 'short board' frame, just came in. Looks dry today so I will give this some thought, perhaps I am over complicating over thinking the whole process, and take a crack at it tomorrow. I get hung up on the parting of something that big, I know I don't have the capacity to do that depth using round stock.
I have 1/4" plate. So...
Hole saw the blank.
Hold it against the chuck and do the OD.
Chuck it up and do the face, recess, and bore to 5/8".
Flip it over press against a precision ring for perpendicular, indicate off OD and center. Trying to hold and indicate off <.25" seems difficult use center hole?
Turn second face and then turn recess.

Does this sound correct?
Thanks for all the helpful suggestions.

Toolguy
10-06-2018, 02:05 PM
Hold against chuck with live center in 1/4" hole from hole saw and do OD, face to thickness and recess. Flip over and hold against chuck and do recess. Put part in lathe chuck, square up by pushing with drill chuck face. Drill center hole to 5/8" last. No indicating, no making precision ring.

darryl
10-06-2018, 04:26 PM
I gather the OD is not critical either. I'd just hole saw or cut out a slightly larger disc than required, mount and face one side, doing the recess at the same time. Create the center hole to about 9/16. Turn it over and remount it, using the hole to center it. Then face it to thickness, leaving a bit of a ring on the outer edge so you don't cut into the jaws. Turn the recess in this side and bore the hole to 5/8. Now you turn a spud to mount this disc on and hold it to the face of the jaws with pressure from the tailstock. Now you can turn the OD to remove the ring and expose the proper thickness. If the faces of your jaws run concentrically, the disc will also become even in thickness. Everything should be concentric at this point. Just another way to go about it.

CalM
10-06-2018, 11:39 PM
Write yourself an operations list. from raw materials to finished piece. Think carefully about how each operation can be best done securely and accurately.

Then, read through your list with an eye for how it can be improved and which operations might be juggled for ease and accuracy. After all, it is only you who knows your tooling and capabilities.

After a thorough review of your best plan. Post it here for commentary and suggestion.

Working someone else's plan is no real benefit to you. especially if it fails. If the results are good, you end up with the part. Not that there is anything wrong with that.

I have found that writing an op sheet helps me plan work better than just about any thing other than farming the job out! ;-)

winchman
10-07-2018, 02:36 AM
Dado sets used to come with flat washers and paper shims that work well for spacing blades.

https://cdn-tp3.mozu.com/24645-37138/cms/37138/files/2122debf-a6e3-422f-b692-a831e321e3ab?quality=50&_mzcb=_1535131854392

Joe Rogers
10-07-2018, 07:52 AM
Depending on what your aim is while cutting, you may be way over thinking this. How precise are the blades you intend to shim? The blade wobble on most offers is significant. Id get a washer to fit the arbor that is close to flat. Install it and check the runout with a dial indicator. If the runout was excessive in your experiment Id stone the washer leaning on the hi spot. Done.
Have you calculated the tooth set and/or blade tips into the numbers? Are the blades matched.
Joe