Can't get mitre's right... need a new TS?

[Justin Florentine]

I currently use a Rockwell (yes, it's that old) 34-410. I've been trying to build a custom picture frame, but have not been able to get accurate mitres. In my tests with 3" wide boards, I'm off by a full 1/2" about 30" out.

I've tried breaking this thing down multiple times, and cleaning all the contact surfaces. Anything that needs to slide gets paste waxed. I've tried PALS on both the front and rear trunnions. I've got machined pulleys and a V-Twist belt, but this thing still rocks right back out of alignment. or as I like to refer to the +-.020" I can get it within; "malignment". I've even tried adding locknut washers between the trunions and the table deck to increase the "bite", but to no avail. Any other bright ideas I don't know about?

The most time consuming part of this process is far and away the continuing maintenance of this saw. I've overhauled it twice in the past 6 months since purchase, and I've tried everything I can think of to align it and keep it aligned. The best I can get it is .015" off from front to back, and it doesn't stay even that close after I put the motor back on and run it a few times. Meanwhile, I have $100 worth of cherry that I can't turn into a picture from for Mom.

It may have been a great piece of iron, and would probably make a great dedicated dado table. I'm afraid the time I've spent accomplishing almost nothing which requires precision is unacceptable; it's taking a lot of the fun out of the hobby. I'm pretty sure there is a Jet Proshop or a Grizzly hybrid in my near, if not immediate future. If anyone has any suggestions as to how to determine if the 34-410 is salvageable, I'd love to hear it. I've got dial indicator jigs and digital calipers for measuring minutae.

[Nancy Laird]

I'm pretty sure there is a Jet Proshop or a Grizzly hybrid in my near, if not immediate future.

Justin, I can't help you with the problems you are having with the Rockwell saw, but before you buy anything, be sure to check out the Steel City saws. They make a hybrid that puts the Grizzly to shame!

[Jason Beam]

Justin - i gave up on the very same issues you've been having. I came up with a miter sled that has a 90 degree triangle that gets split at the corner by the blade. that way I can use it to cut complimentary angles instead of needing to be dead on. Has gone a long way toward making my miters much more accurate :)

[John Eaton]

I think you'd be hard pressed to get a good miter on any tablesaw without a sled. It's not really what a tablesaw is known to be good at cutting just using a miter gauge. If your sled is square to the blade and each side is perfectly 45 degrees to the blade, I'm betting it'll fix your issue with the saw. Me, I cut my miters "loose" on a CMS and then sand them to 45 using a jig on the disc sander - works every time.

-- John

[Justin Florentine]

Got any plans for sleds (mitre or crosscut) you'd endorse? I'm concerned about this since I can't really square the blade to the mitre slot reliably and so I'm afraid I'll have a hard time squaring the sled. I like the idea though, especially when compared to the cost of replacing a saw.

[Ed Sallee]

I just purchased a sled & miter gauge....what difference. See this thread http://www.sawmillcreek.org/showthread.php?p=903153#poststop
I put it to the test a little yesterday....made a lid for a box that turned out Great..... so far.

[Jim Becker]

You need to make a miter sled...about the best way I've found to do the miters for framing because you can insure complimentary angles and tight joints as a result.

[Nissim Avrahami]

Hi Justin

Welcome to the forum

I cannot help you with the alignment problem...I really cannot understand why the alignment is changing if everything is tight...

Anyway, maybe instead of "instrumental alignment"......."listen what the blade have to tell you"...measuring with instruments has a few variables that anyone can change the readings that you get and nobody said that you'll get what the reading says.

You can try to align the blade to the miter slot using this method that takes into consideration all the "Run-outs" of the blade, arbor and blade fluttering...I call it "Dynamic alignment"...
http://www.sawmillcreek.org/showthread.php?t=89490

Once you align the blade to the miter slot...."Forget About The Blade", I mean, all the other references like, the miter gauge fence, Rip fence or the Sled fence should be referred only to the Miter Slot....So, when you set your Miter Gauge to 45° - it should be 45° to the Miter Slot (NOT the blade)

Even if the blade will be "OFF" parallel to the miter slot, it will not effect the straightness of the cut...yes, it will effect the cut Quality i.e. you'll get rough cut or burn marks.

If you want to get perfect square and perfect mitered connections for a picture frame (and please note that I did not say "perfect 45°") you should use a sled and cut the members with the "Left" and "Right" method.

To see how to make the sled fast and easy please go here
http://www.sawmillcreek.org/showthread.php?t=64448

To cut picture frame miters with the sled, please have a look here (wow, it's my first post in SMC)
http://www.sawmillcreek.org/showthread.php?t=36590

That's how the sled looks and what "he knows to do"
http://i158.photobucket.com/albums/t104/nanikami/TS%20Miter%20sled/11.jpg

http://i158.photobucket.com/albums/t104/nanikami/TS%20Miter%20sled/12.jpg

http://i158.photobucket.com/albums/t104/nanikami/Glass%20table%20WIP/010.jpg

Regards
niki

[Rob Cooper]

Nissim,
Great sled and tutorial. I am going to try your method after some recent mirror frame frustrations.

[Nissim Avrahami]

Thank you Rob

......I see that you are also from the "Welcome to the forum".... :)

So.......

Welcome to the forum Rob

Regards
niki

[Justin Florentine]

Nissim, thanks for the ideas. I really like the idea of folding the inaccuracies into one calculation. I also like the cost of a custom sled as opposed to a brand new saw.

I was looking at the crosscut mitre sled from Rockler because it is on sale, but it is left side only, so I wouldn't be able to complement any errors by cutting on each side.

[Cliff Rohrabacher]

Do you have adequate meat on the mounting lugs to drill and ream for dowel pins after you dial it all in to about a thousandth of an inch of accurate?

Dowel pins can give you an deadly accurate and repeatable location point for any metal parts that have to return to true after disassembling.

This so long as the other parts are not warping or cracked.

It's entirely possible that a magnaflux of your trunnion may reveal a cracked part which a weld may make good again.
I say this 'cause you talk about being unable to get it closer than 0.015" true and if you are doing it right then that just makes no sense.
So I'm guessing that there is at least one other problem playing into the party that you haven't seen like a micro crack.

It could also be that the mounting surfaces have been n mistreated over the years and are not flat. This of course would make getting the machine to true-up impossible.

The spot faces where the machine bolts together have to be flat. If they are convex or deformed you gotta flatten 'em.

Another possibility: If they have got themselves worn so that they tend to "key" into deformities ('cause some snapperhead bolted 'em together with chips of steel in the joint) then those deformaties may forever defeat you attempts to true the machine up. Either take 'em to a machine shop or take a file to 'em or take a spot facer to 'em on your drill press.

A little angularity out of true on the mounting surfaces isn't going to trash the party. The bolts will bring faces together if they are a little out of angular true. Cast Iron does flex a little. Just don't ask it to flex a lot.

[Matt Day]

I bought an Incra Miter Guage (2000SE I think) and have made a number of picture frames with it, and have been happy with the results. A good, accurate, miter gauge is very nice to have for more than just miters too.

[Justin Florentine]

Do you have adequate meat on the mounting lugs to drill and ream for dowel pins after you dial it all in to about a thousandth of an inch of accurate?

Yes, that would be possible I think. The trunnion mount holes are a full 1/8th inch bigger than the post holes, so I might as well ream them out.



It's entirely possible that a magnaflux of your trunnion may reveal a cracked part which a weld may make good again.
I say this 'cause you talk about being unable to get it closer than 0.015" true and if you are doing it right then that just makes no sense.
So I'm guessing that there is at least one other problem playing into the party that you haven't seen like a micro crack.

Yeah, my DI needle fluctuates pretty wildly when I'm locking the bolts down, even a quarter turn at a time. So a cracked trunion eh? Ugh.



It could also be that the mounting surfaces have been n mistreated over the years and are not flat. This of course would make getting the machine to true-up impossible.

I went over these surfaces with steel wool. How can I determine if this is the case? I have a digital caliper, so I assume I would take many readings across the surface with that?

Thanks for the advice all!

[Cliff Rohrabacher]

I went over these surfaces with steel wool. How can I determine if this is the case? I have a digital caliper, so I assume I would take many readings across the surface with that?

Sight it using a light and anything flat like the edge of a chisel or the but end of your steel rule.

With a little practice you can tell between .005" and .001" just judging from the light that gets under the edge.

[Justin Florentine]

Sight it using a light and anything flat like the edge of a chisel or the but end of your steel rule.

With a little practice you can tell between .005" and .001" just judging from the light that gets under the edge.

So I did the chisel/light test, and it's way off. The mounting surface of the trunnion is irregular, I'm not sure by how much, but it's pretty clear. The surfaces of the mounting lugs in the deck are also mighty irregular, but they are also (partially) covered with paint. I suppose I could sand those down with steel wool, but I'm concerned that I would just be introducing new irregularities at a different depth.

I'd also be willing to take both the deck and the trunnions to a machine shop and have the mounting surfaces ground down, but I'm not sure how they'd get everything down to the same heights...

Can that be done, or am I out of options?

Thanks for all the help everyone, I feel a little better at least knowing what the (or at least this) problem is.

[Phil Thien]

I'd also be willing to take both the deck and the trunnions to a machine shop and have the mounting surfaces ground down, but I'm not sure how they'd get everything down to the same heights...

Can that be done, or am I out of options?


Well, anything can be done at a cost. I'd check the bottom of the table with a straight-edge (the blade from a Starrett comb. square is a great straight edge). And I'd check the trunion, too.

Now, if the table is good and the trunion is off, you can lap it using a large (18") tile covered with sandpaper. Don't laugh! You'd be amazed how fast you can cut cast iron with sandpaper, and how flat you can get it using a tile.

If the table isn't flat, then I kinda suspect a new table saw is in your immediate future.

[Justin Florentine]

So this evening, I broke down the entire saw, and spent about an hour's worth of elbow grease with some steel wool on the mounting surfaces. I cleaned off all the rust and most of the paint. I locked down one of the front trunnion bolts, and left the other 3 hand tight. I only installed PALS on the rear trunnion because I can't get to them in the front anyway.

The trunnion holes are oversized all the way around the post holes, allowing the trunnion to be adjusted forward and backward the same amount it is adjustable side to side. I have no idea how this design was intended to work, but it seems that there is a good amount of play towards and away from the arbor. So much that when it's broken down and I wiggle the works, I can see the trunnion rail slide in and out of the trunnion. I suspect that this is causing some of the problem here. If anyone has experience with these old Rockwell saws, I appreciate knowing if this is a known issue.

So now my front trunnion is locked down, and I'm out of play by about .040 when I crank it all the way to the right. I assume this means I'll need to adjust the front trunnion over more to give me more slack to adjust from the rear. I'll take one more crack at it tomorrow night before declaring "good enough" and moving on to make a mitre fixture sled.

Any idea what the tolerance is in a situation like this? Am I gonna frustrate myself trying to get a descent 45 mitre if I can't get the runnout under .010?

[Wayne Cannon]

In addition to the miter sled suggestions, use a sandpaper face on the fence surface (miter gauge or sled) and/or clamp your work to the fence. Otherwise, the work will frequently slip slightly while cutting at the miter angle -- enough to mess up an otherwise good miter joint.

[Howard Acheson]

Inaccurate miters is almost always an issue with the miter gauge.

Either the miter gauge is not set to exactly 45 degrees or the board is sliding along the face of the miter gauge as you make the cut.

First, deal with the slippage. Using a spray adhesive or double faced tape, apply 120 grit sandpaper to the face of the miter gauge. This will stop the slippage.

Next, are you sure your blade is set exactly (within 0.003" or less) parallel to the miter slot? If not, adjust the position of the trunnion until you get it right.

Now, put a 45 degree drafting triange against the blade plate and against the miter gauge face and set it to 45 degrees.

To make and accurate picture frame you must start with a two pairs of boards of exactly the same width and each pair must be exactly the same length. You should be cutting the boards to length as you cut the miter. Use a stop block on your miter gauge. Fit the pieces together and if they don't fit, slightly adjust the miter gauge angle to correct.

Finally, for picture frames it is much preferred that you use a crosscut sled so you don't have to adjust your miter gauge. Cuts are much more accurate and repeatable.

[Justin Florentine]

Inaccurate miters is almost always an issue with the miter gauge.

Either the miter gauge is not set to exactly 45 degrees or the board is sliding along the face of the miter gauge as you make the cut.

First, deal with the slippage. Using a spray adhesive or double faced tape, apply 120 grit sandpaper to the face of the miter gauge. This will stop the slippage.

Yes, I'll be attempting this first before I build a sled. Right now I'm still recovering from the 3 hours spent trying to get the motor pulley off the motor. It was cracked, warped, egged, and fused right onto that axle. A nice machined aluminum one is waiting to be applied once I clean off that axle.



Next, are you sure your blade is set exactly (within 0.003" or less) parallel to the miter slot? If not, adjust the position of the trunnion until you get it right.That's a good one. Alignment of this table/blade has been an ongoing ordeal, and the best I have been able to get it is .015", and I constantly debate if that makes this a lost cause. I have a couple of new theories as to why this may be, and I'm hoping that putting new pulleys on further up their respective axle/arbor will keep this from falling back out of alignment so quickly.



Now, put a 45 degree drafting triange against the blade plate and against the miter gauge face and set it to 45 degrees.

To make and accurate picture frame you must start with a two pairs of boards of exactly the same width and each pair must be exactly the same length. You should be cutting the boards to length as you cut the miter. Use a stop block on your miter gauge. Fit the pieces together and if they don't fit, slightly adjust the miter gauge angle to correct.

Finally, for picture frames it is much preferred that you use a crosscut sled so you don't have to adjust your miter gauge. Cuts are much more accurate and repeatable.

[Bruce Wrenn]

Justin, I have rebuilt the same saw. I had to use two 24" clamps to clamp front trunion to rear trunion, before tightening down any of the bolts. This way, whole assembly moves as a unit. Wear in the curved grooves will allow for the parts to drop down. I had enlarge the bolt holes also. Do build a sled, or spring for a Dubby.

[Ed Gerken]

This thread inspired me to take another crack at aligning my Montgomery Ward TS. I inherited it from my dad, that alone makes it a keeper. It's old and underpowered but I've used it for 20 years, I'm used to it and it makes a good cut.

Last time I tried aligning it with the saw upsidedown so I could see what was going on. When I was done and righted it, the alignment hadn't improved at all.

This time, I loosened just one bolt and gave the works a nudge in the direction it needed to go. Success! The other bolts let it move without it slipping back, unlike when I'd tried it with all the bolts slackened.

Have you checked to see if the blade is warped or the arbor or washers bent? If you check alignment against the blade, then remove the blade to adjust and reassemble with the blade and washers in a different, random rotation, you might be measuring blade problems instead of trunnion.

If that's all square and true, perhaps you can align with the blade mounted and clamped to the fence with a board inbetween fence and blade. It may help hold things in position till you can evenly tighten the trunnion.

Try some brass shim stock on the trunnion mounting surfaces. Might take up some slack and give a better surface to adjust and tighten against.

I use a CMS for miters, but I like the idea of the sled shown earlier in the thread.

-Ed

[Justin Florentine]

Justin, I have rebuilt the same saw. I had to use two 24" clamps to clamp front trunion to rear trunion, before tightening down any of the bolts. This way, whole assembly moves as a unit. Wear in the curved grooves will allow for the parts to drop down. I had enlarge the bolt holes also. Do build a sled, or spring for a Dubby.

Positively inspired Bruce. I'm totally going to do that.

I think a lot of the problems I was having when cutting mitres were due to both technique and some insane vibration. I now have cleaned both the motor axle and the arbor and refitted with machined pulleys. I also built a mini torsion box on the cheap and am using that as a platform for the stand since my floor is not level at all (like 1/4" per foot in a lot of places). The blade is reading off by .020", but I seem to be able to get somewhat reliable mitres. I cut a bunch on the right side of the saw using a new gague + sandpaper and saw only a 1/32" of drift over about 26" once assembled into a frame.

I'm about to call that good enough, but I will try clamping the trunions together during adjustment. Thanks everyone for the advice, someday I'll get this thing sandblasted and will post pix after a proper paint job.

...the moral of the story, is that when you find a "deal" on a big old piece of iron on craigslist, noticing that it's been stored year round in a barn should probably be a deal breaker.