We are currently running a Northwood Machine. We are having trouble with our Ogee (Profile F3) tooling. Currently we are using Hexo. It seems to be consistantly breaking our material. To avoid breaking it we have had to run it very slow. Has anyone else had this problem? Do you have any suggestions.

Thanks!
Tori

What do you mean by breaking? 

On occasion we have corners try to break off from the up force of the OG, on really flaky stuff, if we can't get a pod close enough to the edge.


Are you guys breaking sink rails?  We always OG the edges before we drop the sinks. 

fwiw

We have a lot of corners breaking. Do you just have your opperator manually slow it down on the corners. What are your feeds and speeds? Do you use a 45 breaker bit?

We also have issues that we need to run the first bits sooooo slow otherwise it pushes the material. We use a good amount of pods under the piece so I don't think that is the issue.

On the sink rails we run the edge first and then cut out the sinks, we haven't seemed to have a problem with breaking on that. We typically have 3 3/4" to 4" set back on all of our sinks and we ALWAYS use the narrow sink supports between the sink and the edge.

A little more information would be helpful. Do you know what feed rates and rpm you are running the tools at? Do you know how much material you are taking off with each tool? Is the breakage always happening with the same tool and same profile?

if you're running a Northwood then you're probably using Stonevision. There is a setting in there that will automatically slow the feed rate down on corners.

I run a 45 degree breaker before the P1 Ogee at 50ipm.   Then we run two passes with the P1.  First pass is .155 off the finished line and second pass is .03 off the finished line.  P1 runs 50 ipm and isn't set to slow down around outside corners.

Are the parts that are moving the same ones that are experiencing the breakage?  If so , then your probably  just losing vac when the crack opens up.


How close to the edge are your pods?  Then only time I have had it happen, was with a wierd bumped out corner that didn't allow a pod to get close enough to the edge.  Fortunatly it was Sedna and we were able to top polish the area and save the piece (9 foot long Island )

edited by moderator

The others have already given good advice.  The Ogee (and some asymmetrical profiles) can put uneven forces on the stone.  On fragile materials, this can result in breakage or parts moving.

Another tip could be to add a profiled breaker (frangi or similar) to pre-shape the edge and remove more material before the P1 comes in.  Alternately, running multiple partial-depth P1 passes will lessen the up-forces (and the breakage).

USE A FRANGISTONE AND A FEW PREPASS ON POS 0 AND 1