Is anyone doing any side-cutting toolpaths?

Topics related to wrapped rotary machining in Aspire or VCarve Pro
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Rcnewcomb
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Is anyone doing any side-cutting toolpaths?

Post by Rcnewcomb »

Is anyone doing side cutting with their indexer, i.e. cutting from the left or right rather than the top?

I've been thinking about some alternate machining strategies but wanted to know if people had experienced material holding issues with toolpaths that were something other than top center axis.
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garylmast
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Re: Is anyone doing any side-cutting toolpaths?

Post by garylmast »

Hello Randall, I have model a few cars and trucks and have used my indexer many times to turn the model on each side so I could cut the wheel wells, being just one of many examples I use the indexer to support the material. Gary

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Re: Is anyone doing any side-cutting toolpaths?

Post by rscrawford »

Rcnewcomb wrote:Is anyone doing side cutting with their indexer, i.e. cutting from the left or right rather than the top?

I've been thinking about some alternate machining strategies but wanted to know if people had experienced material holding issues with toolpaths that were something other than top center axis.
I've cut on the side, using a 1/2" bit with a 2" cutter length. Gives a much better cut than end milling on the top. This way you can use a profile cut and get the shape in a single pass, rather than using a finishing toolpath on the top. With long, thin pieces this will give some chatter as the wood flexes, so you have to play around with speeds and passes.

Another technique that works well is to cut slightly off centre on the top, so you are using more of the edge of your cutter rather than the end as the indexer turns.
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Re: Is anyone doing any side-cutting toolpaths?

Post by spinningwood »

Randall - I've cut from the side two different ways with different machines I built in the past.

Way 1 (I think this is what you are asking about): Cutting tool mounted vertically but moved off the center line of the part and cutting on the side (of the cutter and the work). I use the same chucks and tailstocks on my rotary axis as I use on my wood lathes. Work holding is not an issue. Using a cutter or cutting motion that provided a force perpendicular to the axis of rotation could overwhelm and drive the rotary axis. The farther you are cutting from the centerline the greater the leverage and the easier it is to drive the rotary with the cutter. Things like vertical plunges or use of upcut / downcut bits were dicey. The greater the holding force of your rotary, the less of an issue.

I also found designing rotary work, in Aspire, that cut below the centerline to be a pain in the .... well, let's just say not as much fun.

I abandoned the ability to cut off the centerline in the latest machine I built. Makes things a lot simpler. What I really want is a 5-axis machine and software that will support undercuts. That's not in my budget though.


Way 2 (but maybe you were asking about this): Cutting tool mounted horizontally, cutting on side of work but with tool on centerline. This is the same as cutting on the top with the tool mounted vertically. This design had some real advantages with very heavy routers. I didn't need a counterbalance system and the Z (although horizontal I still defined it as Z) axis could be geared for much faster movement without me having to worry about the stepper being overwhelmed by gravity. If I had unlimited floor space in my shop I would have stayed with this design. But I don't and I ended up going back to a vertical arrangement to save space. But I'm now designing my next machine which will be a very small format (10" max spindle length, 2" max diameter) and I'm going to use a horizontal Z. In this case it will make it easier to mount / dismount the work and to monitor cutting.

I should note that I don't use a rotary axis attached as a 4th axis to a standard flat bed CNC. I do enough rotary work that I've been building dedicated 3-axis machines (X, A, Z) for rotary work for myself.

Ed

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Re: Is anyone doing any side-cutting toolpaths?

Post by dealguy11 »

The guys at Legacy have worked out most of the most effective ways of cutting on the rotary. For profile type work, they generally recommend cutting generally on top with the tool just off the centerline of the part. They generally do cutting from the side for things like reeding, using a reeding bit made for that purpose, which cuts fast and leaves a nice finish.
Steve Godding
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