LumberJocks

When 45º isn't...

  • Advertise with us

« back to Woodworking Skill Share forum

Forum topic by Kelly posted 11-06-2017 01:22 PM 570 views 0 times favorited 14 replies Add to Favorites Watch
View Kelly's profile

Kelly

65 posts in 1641 days


11-06-2017 01:22 PM

I’ve been trying to cut some boxes and something is a little off. I cut some 45º miters but they appear to be cutting at less than 45º even though both my square and digital gauge show the blade is at 45º. The drawing shows what I’m ending up with.

I ran all the lumber through the jointer (I checked that for square too) so as to start with a square edge, but somehow am losing a degree or two when I’m cutting the miters.

Does anyone have any ideas what might be going on?

Thanks,
Kelly!





I drew this using 44º miters, to show what is happening. I’m not sure what the exact angle is but the effect is the same, with each corner being greater than 90º.



14 replies so far

View mahdee's profile

mahdee

3828 posts in 1600 days


#1 posted 11-06-2017 01:28 PM

Many times the wood has a tendency to move as it is being cut with the blade tilted. clamp the wood to the miter before running it through.

-- earthartandfoods.com

View Lazyman's profile

Lazyman

1493 posts in 1220 days


#2 posted 11-06-2017 01:33 PM

Is your insert flat? Make sure that it doesn’t have a bow in it and is adjusted perfectly level with the table. You could try making a quick and dirty sled and see if that helps.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View dhazelton's profile

dhazelton

2607 posts in 2129 days


#3 posted 11-06-2017 02:05 PM

If you crosscut all your pieces on a sled then you can cut the mating joints on the opposite side of the blade so no matter what you have a 90 degree joint.

View Rich's profile

Rich

1969 posts in 422 days


#4 posted 11-06-2017 02:47 PM


If you crosscut all your pieces on a sled then you can cut the mating joints on the opposite side of the blade so no matter what you have a 90 degree joint.

- dhazelton

Bingo. +1

-- No matter how much you push the envelope, it'll still be stationery.

View jonah's profile

jonah

1441 posts in 3131 days


#5 posted 11-06-2017 03:08 PM

+1 as well. You can also do the same thing with a miter gauge if you can use it on either side of the blade.

So long as you end up with complementary angles, it doesn’t really matter if they’re 45 degrees or not.

View rwe2156's profile

rwe2156

2707 posts in 1313 days


#6 posted 11-06-2017 03:17 PM

Check that ZCI for flush to top.

The wood needs to be dead flat. If this is not the case, using a sled won’t help.

If you’re just running the wood through there could be another cause. A left tilt blade with fence on right will have tendency to lift wood. Counter this with a push block to keep the wood pushed down against the table.

-- Everything is a prototype thats why its one of a kind!!

View splintergroup's profile

splintergroup

1685 posts in 1055 days


#7 posted 11-06-2017 03:27 PM

The complementary angle approach is a winner, but any method requires consistency. Aside from the usual issues with square stock, make sure (clamp) that your stock is secure to your miter gauge and doesn’t move during the cut.

When using a stop block to cut the opposite miter, have the stop block register to the stock some where in the center of the miter, not the tip (think of an “L” shaped stop).

Cut some scraps to the same size and use these to tweak your blade angle before you begin cutting your box pieces.

View waho6o9's profile

waho6o9

8025 posts in 2409 days


#8 posted 11-06-2017 03:44 PM

+ 1 for splintergroup. I like using Bessey hold down clamps.

View MrRon's profile

MrRon

4487 posts in 3076 days


#9 posted 11-06-2017 06:11 PM

Any “Wixey” type gauge or 45° triangle is never perfect. Just being off by a few minutes, can make a difference. Blade runout, fences, miter gauges can all have a minor inaccuracy and it can add up to a less than perfect miter cut. A 45° miter cut on 3/4” wood that is off by as little as 1/10 of a degree or 6 minutes, will leave a gap at the miter of almost .004”.

View Loren's profile

Loren

9602 posts in 3480 days


#10 posted 11-06-2017 06:16 PM

The family of jigs exemplified by this example can help dial in miter cuts.

If I were making miters often I would want
a disc sander. They’re good for fudging
miters. A donkey’s ear shooting board can
be used as well.

Also, contractor type table saws usually heel
when tilted due to the weight of the motor
pulling unevenly on the trunnions.

View Lazyman's profile

Lazyman

1493 posts in 1220 days


#11 posted 11-06-2017 06:44 PM

If you cannot tune up the saw to fix this, you may be able to fix the boards after cutting using a miter shooting board. Cut them a smidge long and trim to final length with a hand plane and shooting board.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View Kelly's profile

Kelly

65 posts in 1641 days


#12 posted 11-06-2017 09:15 PM

Thanks for your input! You have given me several options to consider as I narrow down how best to address this problem. One thing I didn’t make clear is that the mitered edge on this project was 16” long, I realized that in my drawing it doesn’t look that long. So cutting from a sled would probably be more difficult than just running the wood along the fence. Also, the wood is very soft (pine) and 1/2” in thickness. But, that being said I’ll start with making sure the ZCI is dead flat and through your suggestions.

Any other ideas/input is welcome!
Thanks again!

View poospleasures's profile

poospleasures

629 posts in 2317 days


#13 posted 11-07-2017 12:15 AM

I very seldom tilt the table saw blade. I made a 45 degree (adjustable ) about 10 or so years ago and tinkered with it until perfect and have made hundreds of boxes with it and every miter joint is exact. I don,t have a picture of this jig, but if you want to PM me I will make one and send it.

-- I,ve had amnesia for as long as I can remember. Vernon

View sawdustdad's profile

sawdustdad

333 posts in 718 days


#14 posted 11-07-2017 01:20 AM

Not mentioned, but equally important as the angle is consistent lengths—be sure each side of the box is the exact same length. I use stop blocks on the sled to be sure exact lengths.

-- Murphy's Carpentry Corollary #3: Half of all boards cut to a specific length will be too short.

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com