WaltS your not alone

[martin54]

After the problems that Walt had with the bowl he was making I thought I would post this just to show that he is not alone when it comes machining problems with bowls
Because I wasn't 100% sure how best to machine the outside of the bowl I set about machining just the inside of the model using a boundary vector, went really well & I was really happy with the level of detail & the fact that there would be very little in the way of sanding.
After the inside was finished I left it on the machine overnight & then carried on with it today machining the outside.
Things started very well & the outside was looking great as well, there was a sudden strange noise & lucky for me I was close enough to hit the emergency stop before any real damage was done. The work piece had moved on the router table & when I checked the clamps were not that tight at all, don't know if they had worked lose as it machined but in future I will check the tightness of clamps periodically on long jobs. I wasn't convinced I would be able to re align it properly on the router table so off it came, might try a rescue job in the future.
Shame really because I think it would have been a really nice piece once completed.

[dwilli9013]

Ouch!! All is not lost. What I would due is glue it down to a waste piece. The profile cut out the sides. Will still make a really nice Trivet.
Thanks for letting us know the pros error also.

[Leo]

I have to agree, that is not a total loss. I would try yo save it. There may be some possibility to do an outside profile of sorts but you will need to be creative to do it.

That is an awesome design and it would be a shame to lose it.

I would be interested in how well it hold up after stress relieving for a while. I know bowl turners will rough out a shape and let it sit for a year before finish turning.

Making bowls is on my to do someday list.

[scottp55]

Martin,
If it was me, I'd say the CNC work was done and some "Creative Sanding" was called for
Who said the wood wanted to be a uniform height/wall thickness "bowl"
A totally unique freeform piece sells for more(don't forget to sign it)
NICELY done interior!

[martin54]

Not sure when I will get round to it but as I have a lot of other stuff I would like to try I will put it to one side but something will be done with it, I can either try putting it on the cnc to finish or the other option might be to see if I can mount it on the lathe & finish it that way

Dwayne, thanks hadn't thought of something like a trivet was still in bowl mode Think that would be a last resort though.

Leo, that is a standard Aspire model just pulled from the clipart As for stress relieving having recently acquired a shopsmith machine I have been doing some turning & have watched quite a few videos where people say they rough out & put to one side for a year or so before remounting & finishing but it seems to be more common with very thin walled bowls & free form turnings or when using green or air dried wood. I also don't know (yet) if certain woods are more prone to distortion than others. I made a bowl for my Mum when I was at school so it's over 40 years old now & still seems to be the same shape it was when I finished it
I don't have a rotary axis & fitting one to my machine would require major surgery which I haven't ruled out but I can't see happening anytime soon so unfortunately I won't be able to make bowls like some I have seen on the forum.

Scott, there are 2 problems with your suggestion, the walls are already quite thin so trying to turn it into a freeform shape may end up looking like it was just a very bad finishing job ......... & secondly I hate sanding
I am however happy with the selling for more part of your comment although if I signed it I would probably knock money off the value

[Paul Stewart]

Nice work sorry for the problem for such a nice piece.
If you use use Mach3 there may be a solution to find the center using the big tex blue probe screen.
It involves editing the script file for the probe button.
PM me if you need more details.

[martin54]

That's interesting Paul seeing that as not only do I use mach3 but I also use the big tex screenset

[Paul Stewart]

Martin54
Good to here you use both
attached is a copy of my edited script for the probe button. Changes are noted by ( ) around edited text in script
the theory is to put your probe plate (thin tin foil may work better) on the inner edges of your bowl hit the probe button, (moving probe plate to new location each time )
My edited script file will move (10 inches ) in my edited script file in both the x and y directions then go to center.
this should work but try this at your own risk i'm not responsible for any machine damage or mishaps
i have tested it on my machine for theory purposes and seems to work.
to edit script go to (at top of the main Mach3 screen)select operator - edit button script - then hit the probe cross hairs it will open up the edit screen so you can modify it (don't forget to save)
you can change setting to your needs feed distance feed rate ect. for your machine
Hope this helps
Paul

[martin54]

Thanks Paul will have a look at that when I have some spare time. Might not get used for some time with this project though

[COWBOY1296]

I am always tightening my clamps during different toolpaths, which may have caused a problem in one of my carving. It was a 3-d plaque surrounded by v-carving on a flat area. i noticed that the v-carving was deeper on one side than the other. My guess is that this was caused by tightening one side more than the other. Next plaque off of the router, no problem.

[martin54]

I am always tightening my clamps during different toolpaths, which may have caused a problem in one of my carving. It was a 3-d plaque surrounded by v-carving on a flat area. i noticed that the v-carving was deeper on one side than the other. My guess is that this was caused by tightening one side more than the other. Next plaque off of the router, no problem.

I have never tightened the clamps part way though a job since I started using the machine but when I went to take this off the table they felt really lose which made me think that they had some how worked lose while the machine was running. This was a thicker piece of material than anything I have previously machined, I normally run with very conservative figures for my cutting bits, not really sure why because I know the machine is capable of a lot more.
Because of the thickness I was cutting & the time the roughing cut was going to take with my usual figures I upped the DOC by quite a bit to reduce the roughing cut time. I thought that by doing this I may have caused the machine to vibrate more than normal which could explain the clamps coming lose.
Interesting what you say about the vcarving on one side of a project being deeper than the other, do you try to tighten the clamps evenly ?

[COWBOY1296]

From now on i will clamp them evenly, but before then i was not paying attention.

[adze_cnc]

All this reminds me of a time when the hold-down system let go cutting the second size of an oak bowl. Images show a 3.5 inch oak blank that lifted up and impaled itself on the long router bit. I stopped it just in time. I continued on carving the outside the already half-carved bowl and all went well.

Steven

Oak blank impaled by router bit

How deep?

Oblah-di, oblah-dah. Life goes on.

[dwilli9013]

All this reminds me of a time when the hold-down system let go cutting the second size of an oak bowl. Images show a 3.5 inch oak blank that lifted up and impaled itself on the long router bit. I stopped it just in time. I continued on carving the outside the already half-carved bowl and all went well.

Steven

Impaled.jpg

ImpaledLength.jpg

ImpaledLifeGoesOn.jpg

Good save at least you didn't have to tack it to the wall of shame.
Always good to see even the pros are human.