Square Cross Cuts

[golf76]

Need Some Help

Having a problem getting square cross cuts. Boards have been jointed so the broad and narrow sides of the board are flat against the table and the miter. Each side of the blade appears to be parallel to the edges of the throat-plate recess, at both the front and back positions. Miter gauge is square to the blade.

But when I put a square on the end of the board after I make a cross cut, the leading edge of the board (the edge that enters the blade first) is off by a bit less than 1/32” of an inch compared to the back. Not exactly square. I’ve even allowed for some minor play in the miter gauge to the miter groove by holding the miter tight against one side or the other of the miter groove.

Have checked for wobble in the blade as it circulates but either I'm not noticing it or the movement of the blade is fine. Wondering if the source of the problem is the blade trunnion – haven’t tried to adjust that yet because I’ve never done it before.

Table saw is a Ridgid 10-inch TS3650.

Any ideas?

 

[Phil S]

Your blade is not parallel to the miter slot. Fairly easy adjustment, but take your time and get it within a couple frog hairs

 

[Jeremy Scuteri]

What Phil said makes sense and is worth doing.

FYI, the miter gauge should not really be set to be square to the blade. The miter gauge should be set so it's fence is perpendicular to it's direction of travel (which is set by the miter slot, not the blade). IF the miter slot is set perfectly parallel to the blade, then the fence will also be perpendicular to the blade.

Squaring the miter fence to to the miter slot will always result in square cuts. Squaring the fence to the blade only results in square cuts when the slot is perfectly parallel to the blade.

 

[DaveT]

I had a similar problem and found my blade wasn't parallel to the miter gauge. Once I adjusted my table top all good. Well worth the time it took to do.

 

[Bill Clemmons]

Sounds to me like your work piece is slipping along the miter fence as you push through the cut. That's why the leading edge is shorter than the trailing edge.

Attach an auxiliary fence (flat piece of wood) to your miter fence, and line it w/ some adhesive backed sand paper (anything from 150-320 grit). That should help keep the board from sliding away from the blade.

 

[Ed Fasano]

I agree with Phil S. and Dave T that the blade may not be parallel to the miter gauge slots and therefore out of square with the miter gauge itself. I agree also that the work piece slipping against the relatively narrow face of the miter gauge face is also a likely source of trouble. As the saw in question is a contractor's aw, I doubt that the table top can be adjusted to bring the miter gauge slots into parallel with the blade face. It will likely be a more (but no less necessary) tedious job of re-aligning the blade trunion underneath the table. I would add that whatever method of adjusting the miter gauge to 90-degrees be brought into question. Use of any 90-degree aid that is less than perfectly square (e.g. a hardware store grade combination square) or the marks on the miter gauge itself) will result in results that are equally imperfect. Bill Clemmons’ suggestion of adopting the use of an auxiliary fence (a longer, dead flat piece of wood or MDF faced with sandpaper) to the miter gauge face. I'd also suggest examining the fit of the miter gauge's slot bar. If it is sloppy, its cuts will never be consistent. There are any number of somewhat reliable remedies online (or here). A more accurate after-market miter gauge is another common approach. Even better would be investing the time it takes to construct a dead-on cross-cut sled for use (when possible) in place of the miter gauge. The time it has taken me to build what is now my 3[SUP]rd[/SUP] crosscut sled was time well spent and rewards me with each use.

In the end though, what could be more important than resolving the issue in manner that provides consistent 90-degree cuts?

 

[chris_goris]

Squaring the miter fence to to the miter slot will always result in square cuts. Squaring the fence to the blade only results in square cuts when the slot is perfectly parallel to the blade.

In order to get perfect crosscuts on the tablesaw using a miter slide, BOTH must ring true. The blade MUST be parallel with the miter slot AND the miter slide must be perpendicular. Simply having the miter slide perpendicular to the slot in no way guarantees a square cut. If you exagerrate the whole thing in your head you can rationalize why. If for instance the blade we 10 degrees off square to the slot, it would either push or pull your workpiece along the miter fence as it cut it or more likely at that angle create some nasty kick back. But be off ever so slightly and youll never notice it happening.

 

[Jeremy Scuteri]

In order to get perfect crosscuts on the tablesaw using a miter slide, BOTH must ring true. The blade MUST be parallel with the miter slot AND the miter slide must be perpendicular. Simply having the miter slide perpendicular to the slot in no way guarantees a square cut. If you exagerrate the whole thing in your head you can rationalize why. If for instance the blade we 10 degrees off square to the slot, it would either push or pull your workpiece along the miter fence as it cut it or more likely at that angle create some nasty kick back. But be off ever so slightly and youll never notice it happening.

Not really the case. The miter slot can be "toed out" a bit for the same exact reason the rip fence can be "toed out". Neither should be angled toward the blade (kickback), but both can be angled slightly away from the blade. I didn't understand this for a long time, but using a sliding table saw makes this crystal clear. Cuts CAN be dead square without the miter slot being perfectly aligned to the blade.

Ripping and crosscutting both work on the same fundamental principle. A piece of wood is advanced through the blade in a certain "direction of travel" without being able to rotate. The cut edge will be *parallel* to the direction of travel in ripping and crosscutting operations. Not parallel to the blade, parallel to their direction of travel. This is why you can toe out your rip fence and you don't end up cutting wedges when you rip long boards. The same exact thing happens when using the miter gauge. The piece is advanced along a certain direction of travel and the cut edge is parallel to the direction of travel. In this case, the piece is oriented 90deg to it's direction of travel by the miter gauge fence, so you get square cuts.

Any small mis-alignment between the direction of travel of the piece and the blade (ripping or crosscutting) will actually create a micro-cove on the cut edge. Think of how a traditional cove is created on the tablesaw. Now do the same thing with the angle being 0.01 deg instead of 30 deg or 45 deg. Not enough to care about, but that would be the result of not being perfectly parallel to the blade, not a cut that isn't square.

 

[chris_goris]

Not really the case. The miter slot can be "toed out" a bit for the same exact reason the rip fence can be "toed out". Neither should be angled toward the blade (kickback), but both can be angled slightly away from the blade. I didn't understand this for a long time, but using a sliding table saw makes this crystal clear. Cuts CAN be dead square without the miter slot being perfectly aligned to the blade.

Ripping and crosscutting both work on the same fundamental principle. A piece of wood is advanced through the blade in a certain "direction of travel" without being able to rotate. The cut edge will be *parallel* to the direction of travel in ripping and crosscutting operations. Not parallel to the blade, parallel to their direction of travel. This is why you can toe out your rip fence and you don't end up cutting wedges when you rip long boards. The same exact thing happens when using the miter gauge. The piece is advanced along a certain direction of travel and the cut edge is parallel to the direction of travel. In this case, the piece is oriented 90deg to it's direction of travel by the miter gauge fence, so you get square cuts.

Any small mis-alignment between the direction of travel of the piece and the blade (ripping or crosscutting) will actually create a micro-cove on the cut edge. Think of how a traditional cove is created on the tablesaw. Now do the same thing with the angle being 0.01 deg instead of 30 deg or 45 deg. Not enough to care about, but that would be the result of not being perfectly parallel to the blade, not a cut that isn't square.

This is exactly why you have to exaggerate the geometry to understand it. What youre telling me will NEVER create a clean, straight perfectly square crosscut.

 

[Jeremy Scuteri]

This is exactly why you have to exaggerate the geometry to understand it. What youre telling me will NEVER create a clean, straight perfectly square crosscut.

We are probably getting a bit off topic here, hopefully the original poster doesn't mind. I enjoy this kind of conversation, and we are both being civil, so I don't see a problem. I have one direct question for you:

Does having the rip fence toed out prevent the tablesaw from making "clean, straight, perfectly parallel" cuts when ripping boards?

 

[chris_goris]

We are probably getting a bit off topic here, hopefully the original poster doesn't mind. I enjoy this kind of conversation, and we are both being civil, so I don't see a problem. I have one direct question for you:

Does having the rip fence toed out prevent the tablesaw from making "clean, straight, perfectly parallel" cuts when ripping boards?

Yes

 

[Cato]

Interesting topic. I have put my fence both dead on and as I just adjusted it yesterday I went with a very slight toe out of say 1/64 that is so small I am unlikely to notice anything at all in my projects. Just figured I have more chance of the wood moving as a result of other influences than that small increment that maybe just makes me feel better knowing it is not toed in and chance kickback.

 

[FlyingRon]

Everything should be square. I've heard of people bending the fence away from the blade to avoid kick back but that is NOT a good idea. If you need clearance behind the blade for whatever reason, the better idea is to just not have the fence protrude behind the blade (easiest way is to clamp a piece of wood to the real fence stop stops before the arbor).

Things are a royal pain if things on your saw aren't square/parallel etc... save the headaches and fix it all up now.

The other issue is that your mitre gauge just might not be giving you the support to the piece you're cutting. Buy or build a sled. Can't tell you how much easier it is. Back in the past, I've had the sled on the table more times than it was off (easier to cut small pieces rip or crosscut that way).

 

[CDPeters]

Alot of this depends on technique as well. Assumptions: Miter gauge is square to the miter slot. Blade is slightly out of parallel with the miter slot. Workpiece does not slip on the miter gauge.

If you run your workpiece all the way through the blade, i.e. the trailing edge of the workpiece passes all the way past the front edge of the blade, the cut will be square.

If you stop the workpiece travel as soon as the back edge of the blade breaks the trailing edge of the workpiece, the cut will most likely not be square.

FWIW - my money is on workpiece slippage - DAMHIKT

 

[Howard Acheson]

It sounds like you have not performed your saw alignment in the proper way. The reference for measurements is the miter slot. The following is the way to get your saw properly aligned.

Here is the low tech, low cost way to align a tablesaw that I learned maybe forty years ago and use to teach to my students.

Make 3/4 x 3/4 x 12" hardwood stick. Drill a hole somewhat centered in one end and insert a brass #8 x 1" round head fine thread machine screw about half way. UNPLUG THE SAW. Raise the blade completely up. Clamp this board in your miter gauge (if you determine that there is some slop in your slot to miter gauge, use a playing card to take up the slop) so the screw head just about touches the blade at the front. Now rotate the blade by hand and determine which tooth is the closest. Adjust the screw in or out until it just touches this tooth. Mark this tooth. Rotate the blade so the tooth is now at the back of the table and move the miter gauge/stick assembly to the back and see if it touches the marked tooth to the same extent. If it doesn't, adjust the trunnion (if a contractor saw) or the tabletop (if a cabinet saw) until it does.

For a contractor saw, first use a small c-clamp on the rear trunnion and cradle to keep the assembly from moving. Then loosen the two rear trunnion bolts and one front trunnion bolt. Slightly loosen the other front trunnion bolt and use a stick to tap the trunnion until the blade and screw lightly touch. The blade does not move directly around the center so you will need to repeatedly go back to the front of the blade, readjust the screw, and then again measure the back. Be sure to check after tightening the trunnion as the trunnion frequently moves when being tightened.

For cabinet saws, loosen the bolts that hold the tabletop and tap one corner until things come into alignment.

The same adjustment gauge can be used to set the fence parallel to the miter slot. Slide the miter gauge to the front of the table and move the fence over to the screw head and insert a playing card between the screw head and the fence just so you can move the card as it touches both the fence and the screw head. Now move the miter gauge to the back of the table and see if you have the same feel when you insert the card. I like my fence absolutely parallel--if you want to have a slight opening to the fence, you can easily estimate the opening by adding a thickness of paper to the card.

I always show my students with a dial gauge that their adjustments are within .001 - .002.

You can also use the same gauge to measure blade runout by using a $5.00 feeler gauge.

Finally, after you are satisfied with the above adjustments, check the position of the splitter to make sure it is exactly in line with the blade.

Bottom line, there is no need to spend more than the $0.05 for the brass screw.

 

[Mike Davis]

Howard, just for the hard heads, you are saying the miter slot, the blade, and the rip fence should all be within .001 to .002 inch aligned with each other?

That is how I was taught.

 

[chris_goris]

Howard, just for the hard heads, you are saying the miter slot, the blade, and the rip fence should all be within .001 to .002 inch aligned with each other?

That is how I was taught.

Agreed Mike and thus, your miter fence should end up perpendicular to the blade (or the miter slot or the rip fence) with the tolerance stackup.

 

[CrealBilly]

Howard put it best when he said --- adjust the trunnion (if a contractor saw) or the tabletop (if a cabinet saw). Personally I use a dial indicator and magnetic base affixed to my miter gauge to set the blade, table and fence.

The internet is a black hole - nothing can escape it

 

[Jeremy Scuteri]

I never questioned the idea of squaring the miter fence to the blade until we had the NCWW chat with Mark Duginske back in 2013. He wasn't able to participate live due to some technical issues, but he answered all the questions that we came up with ahead of time. The transcript can be found here: http://www.ncwoodworker.net/forums/content.php?r=150-Mark-Duginske-Bandsaw-Guy-Chat-2013-Jan-17

One question was: "What are some examples of bad information on woodworking that is being distributed on the internet and magazines" One of his responses to this question was "Squaring the miter gauge to the blade"

I didn't understand this at the time, I was really confused by the statement. So much so, that I even tried e-mailing Mark, but I didn't get a response. When setting up a sliding table saw, this concept "clicked" for me and I finally understood what Mark was saying. I just did a quick google search on the topic, and this site (which I have never seen before today) by NCWW's very own Tom Hintz came up. It does a better job of explaining the concept than I did. It even has a video. http://www.newwoodworker.com/squrmitrgag.html


I personally try and have both the miter slot and the rip fence as close as possible to parallel with the blade, without either of them being toed in towards the blade. I find that I get less burning on both the keeper piece and cutoff piece when things are set up as close as possible to parallel, but this is NOT a necessary condition to get parallel cuts when ripping or square cuts when using the miter gauge. This isn't an opinion, this is just the result of physics. The micro-cove that I brought up earlier (and is mentioned by Tom Hintz) is the only non-ideal effect of not being perfectly parallel to the blade and it has nothing to do with the cut being square or parallel.

Kelly Mehler (author of "Mastering Your Tablesaw") talks about the two schools of thought when setting up the rip fence. One schools says make it parallel to the blade, the other school says set it up so it is toed away from the blade slightly. Lots of different ways to skin a cat. We all have our personal preferences, but there is a huge body of evidence to suggest that both ways are acceptable and used by well known successful woodworkers.

I like Howard's setup method. It should give good results and it doesn't require any special tools which is always nice.

 

[Mike Davis]

I would agree to set the rip fence .001 to .002 inch away from the blade at the out feed end rather than inward.

The miter gage should be set 90 degrees to the miter slot.

If the blade is not set parallel to the miter slot and the rip fence then dado slots will be wider than the intended set up.