Horizontal lines from flattening a work piece

[joshua.lynn.thomas]

I have tried a few bits that are >=1” in diameter in my shapeoko 3 xxl, even an Amana. Each time I have used them I get horizontal striations or lines that seem to not go away with several sanding sessions. I looking for any type of advice.



I have attached a picture of some red oak that was flattened with an 1-125” Amana bit (1/4” shank).

Thank you.

[Rcnewcomb]

You need to tram your spindle/router.

From Gary Campbell:
First method:
Surface an area a foot square (raster)
Use a 1) bent Z rod or 2) tram gauge with indicator on smooth blocks at the opposite side of swing, adjust

Second method:
Use a purchased dual indicator tram gauge.
surface with 1 1/4" bit a circular area (on vector spiral ramp) the diameter of the centerline distance of the indicators
calibrate and adjust

Mark Lindsay has a good video on this topic: Tramming the Router
Another video: Is your Router on the Level? - CNCnutz Episode 131

Additional threads:
Tramming Spindle
Tramming (Squaring) Spindle Question

[scottp55]

Perhaps also try a lighter pass and smaller stepover(?)
I'd try a Very small pass depth .005" maybe at 40%, JUST to see if marks are less prominent.
Maybe machine flex, and you'll have to find best pass depth for your machine,and then a Finish pass?
Depends on how much time you want to spend sanding.
Maybe a small test before tramming?
scott

[4DThinker]

It will help to set the direction of a pocket to raster parallel to the grain. You may still end up with a slight scallop if your bit isn't true to the cutting plane, but sanding the board will be simpler.

[scotttarnor]

I took my first shot at flattening a board last night, My first cut had horrible results, I was thinking my tram must be way off. But after thinking about my other projects all coming out pretty good I decided to try changing my settings. So I change from clear pocket offset to clear pocket Raster and decreased stopover. The results were night and day different.

[martin54]

As well as tramming your spindle the other thing you want to think about with large bits like that is the shank size, using a bit with a 1/2" shank will help to give less bit deflection.

I take it you are using a bottom cutting bit

[adze_cnc]

…still another thing to consider with large “flat bottomed” bits or even small ones: can you be 100% sure that the angle between the vertial and horizontal cutting surface is 90 degrees?

[scottp55]

Scott,
Offset Toolpath will show how far off your tram is in BOTH directions....
rastering only shows One direction.
IF using offset and everything is good and millmarks can be rubbed out with finger
(on wood with trued bit) ,then things are Hunky-Dory
Offset toolpath and being able in minutes to remove marks with fingers(MDF)
or with quick 150G on hardwoods is a good feeling
scott

[scotttarnor]

Gentleman, Thank You for your replies, The bit I used was a bottom cutting bit a Whiteside 1/4" shank X 1". When I decided to try a CNC I had no idea if I was going to enjoy it or just play for a week and let it sit on the shelve the rest of the year, so I went with the Piranha LX because it had a small foot print for the garage and it wasn't too expensive. That said I think my tramming precision is limited because really all I have is a Bosch router clamped to the machine, I don't know how precise I can be in adjusting it.
I am wondering where the lack of a precise tram set up will bite me in the future, Flattening a board is now obvious to me, are there other types of cuts or carves that I will have problems with ? Should I always try to use raster rather than offset ?

Thank You

[TReischl]

Well, there is this. . .

You flattened with a 1 inch diameter bit. It will be a rare occasion when you actually use a bit that wide to do carving. About the biggest I run on my machine is .5 dia. That is important because you will see half of the stepping you are seeing with a big wide bit. Also, a lot of carving is done with ball nose bits stepping over a small distance so it will get even better.

If'n it were me? I would not worry about it too much.

But if you are trying to justify getting a bigger, faster, stronger machine? Then heck yes! It is totally unacceptable!

[scotttarnor]

But if you are trying to justify getting a bigger, faster, stronger machine? Then heck yes! It is totally unacceptable!

I love this reply ! 7 months into this and I am already researching !

[scottp55]

Best advice we got when researching what machine to buy was;
"But your Second machine...FIRST"
Looks like you like doing it, and have the touch and thirst for creating:)
T'ain't a bad habit to have:)
scott