TS 55 bevel cut puzzlement

[Lucky Dave]

I make an 8" 45 bevel cut in 3/4  MDF.  Measure the bevel.  Perfect 45.

With no change to saw or to rail, I make a 8" 45 cut in 3/4 hardwood.  Bevel is several degrees off!!!

Whats happening?

In both cases careful to hold saw flat to rail with left hand.

Tried this 4 times, MDF bevels always perfect. All hardwood bevels off, by varying amounts. Some to considerable scorching of the hardwood.

 

[tbellemare]

Feed and speed.

Tom

 

[tbellemare]

MDF bevels always perfect. All hardwood bevels off, by varying amounts. Some to considerable scorching of the hardwood

'Sorry for the abbreviated response, Dave. Dave PM'd me to inform me that I was being too terse (lazy) so here goes...

The first thing I notice is that you're talking about scorching. That's normally caused by the cutter dwelling. In short, it means that the blade or bit is turning and passing against the work piece as opposed to actually cutting it and moving on. This causes heat build up on the work piece and the cutter. It scorches the work piece if it's wood and remelts the shavings if it's plastic. The cutter also overheats and degrades prematurely. The act of cutting produces shavings/swarf that absorb heat from the cutter and "sort of" cool it. Overheated cutters dull prematurely.

There is an ideal relationship between how fast the cutter is moving through that material and how fast it is moving relative to the material it is cutting, "Feed and Speed". With a CNC machine, you literally program "feed and speed". With manually operated power tools, the hand can only reasonably move the tool past the material at a certain pace. However fast that is and it's pertty much the same, relatively slow pace for all material, determines how much "speed" should be set on the tool. Festool tools typically have speed settings from 0-6. If you are scorching the work piece or remelting the plastic, slow down the speed of the tool.

With something like a router, you can fine tune the speed by making it go just fast enough to not chatter at the feed rate you find comfortable. If you like to spin the bit as fast as the router can spin it, you are more likely to burn the work piece. The tolerance zone between too fast and too slow is pretty big for most materials and after you work with certain materials and the same machine, cutter combinations for a while, it will all seem natural.

Tom

 

[semenza]

If the hardwood board you are cutting is not flat it could easily be tilting the rail and thus the saw to varying degrees. And if not a consistent tilt will also be causing the blade to bind (scorching) as it runs along the cut length.

Seth

 

[ccarrolladams]

As Tom B says, when sawing and routing, as well as drilling, it is all about "Speed and Feed"!

In the old days the advantage to power feed drive on drill presses was that an expert could set the rate of every machine operator fed the bit at the same rate.

Long ago we started using power feed on cabinet table saws so that the feed rate was ideal for the material and blade. Of course the same was true with milling machines for metal and routers for wood.

Yes, it does take practice, instruction and some training to get the best results from hand operated drills, saws and routers.

Unfortunately the purchase of Festools does not by itself confer years of experience. It is up to each of us to experiment and practice so we become "at one" with our tools. We try to feel our way through each process.

Oh yes, it really helps to keep actual notes about the speed setting on the tools. Here Festools have a massive advantage because the speed controls the actual speed of rotation under load. It is not just a simple rheostat varying the voltage to the motor. So, with Festools the numbers on the speed dial can be repeated from tool to tool and day to day.

I also teach that we need to become expert using drills, saws and routers before we can effectively program CNC machines. Telling the machine the X and Y coordinates is far easier than answering the Speed and Feed question.

 

[rmwarren]

So my inclination would be to slow both feed and speed when moving from a softer (MDF) to harder (hardwood, i.e. oak or maple) material. Is this the right approach?  ???

RMW

 

[Oldwood]

I would also look at the blade. You can cut MDF with a fairly dull blade, not so much with dense hardwoods. I would try a freshly sharpened blade on the wood & see if that doesn't help the situation.

Gerry

 

[Brice Burrell]

I would also look at the blade. You can cut MDF with a fairly dull blade, not so much with dense hardwoods. I would try a freshly sharpened blade on the wood & see if that doesn't help the situation.

Gerry

I like Gerry's advice.  I think your problem might be deflection, a dull blade really can exacerbate deflection.

 

[semenza]

Several  possibilties  as to the exact reason for the scorching, but what strikes me is the "several degrees"  off on a bevel cut.  In my mind several degrees is not something caused by feed rate without it being quite obvious that the saw is tilting or working so hard that you would just stop making the cut and see whats wrong.

Dave,

How about a little more info?

What blade? Sharp?  What type of wood?  Ripping or cross cutting? Board warped or cupped? Ends of guide rail supported?

Also how much is "several degrees"?

Seth

 

[Lucky Dave]

Hey Guys,

You all are a wonder, I have no idea what a novice would do without this forum. Thanks.  [smile] [smile] [smile]

First, slowed saw speed from 6 to 3 and slowed feed rate. Scorching dramatically reduced. Bevel angle still no good.

Second, changed to new blade.  No scorching, perfect bevel.

Dave

PS: Where does a guy in small town in Western CO go for blade sharpening?

 

[EWTHeckman]

Where does a guy in small town in Western CO go for blade sharpening?

That's a good question. In fact, (at the threat of a thread split) I would like to make this question more general. How do you find places that do sharpening? And how do you distinguish the good places from the bad ones?

 

[tbellemare]

You could send your blades to Leitz Tooling Sharpening Service. To my knowledge, they made the blades.

Tom

 

[pdlandgang]

If the blade seems dull you might want to make sure it is clean especially if you have been cutting MDF.  I have found sometimes that if I get burning and clean the blade it will reduce it.  Something to check.