Can I get a .125 radius on the edge of a part?

[Team Valhalla]

I know what I want, but no knowledge of how it can be done.

I have a piece of ABS type material in an oval shape that's around 12" X 8". Thickness is .125. Slight texture on the A side (don't want scuffed), glossy surface on the B side (can be scuffed). Original thought was to die cut it with a clicker press, but I will end up with a "sharp" edge.

I want to put a .125 radius on the outer edge.

B surface is smooth enough that it could be held down with a vacuum in some way I would think.

What's the best way to do this? Can it be done with a router table of some sort? Table top CNC machine along the line of Shopbot?

It's a production item - annual usage of around 400 pcs or so.

What equipment will do this?

SP

 

[AF]

I know what I want, but no knowledge of how it can be done.

I have a piece of ABS type material in an oval shape that's around 12" X 8". Thickness is .125. Slight texture on the A side (don't want scuffed), glossy surface on the B side (can be scuffed). Original thought was to die cut it with a clicker press, but I will end up with a "sharp" edge.

I want to put a .125 radius on the outer edge.

B surface is smooth enough that it could be held down with a vacuum in some way I would think.

What's the best way to do this? Can it be done with a router table of some sort? Table top CNC machine along the line of Shopbot?

It's a production item - annual usage of around 400 pcs or so.

What equipment will do this?

SP

Haven't touched a CNC in years but perhaps have a custom bit made to do what you want.

 

[iSign]

if the part is just an oval, and by radius on the edge you mean a roundover, then you can get a roundover bit that theoretically could produce a part like this.
By "theoretically" I mean I'm sure that it could be done in several woods, or a number of other plastics... but how well your plastic handles exposing it's core, I couldn't say if it will cut nicely... just that it can be programed to try.

Also, if the material thickness matches the radius, then you don't have the luxury of finishing that roundover before cutting out the part, so on my machine I'd probably ad tape rather than trust only the vacuum

 

[Team Valhalla]

iSign, thank you for the info and education.

Yes, a "roundover" is what I would be looking for. So... a roundover could be put on the edge of the part, but not carry it all the way down to the other surface?

What type of equipment would be required to do this... CNC... table top router... ?

What do you mean "ad tape rather than trust only the vacuum"?

SP

 

[Eric H]

Could be done on CNC, we have a .125 round over bit that comes to a point. It would cut it out and round over with same bit. It's too thin to use a round over bit with a bearing in a hand held router or router table.

 

[Team Valhalla]

Could be done on CNC, we have a .125 round over bit that comes to a point. It would cut it out and round over with same bit. It's too thin to use a round over bit with a bearing in a hand held router or router table.

Eric, Thanks for the info.... answers a couple questions. 1 - Can't do it with a table router. 2 - A bit exists that is able to cut the part out of the sheet and put the round over at the same time.

Is this something that a Shopbot or other small size CNC is capable of?

SP

 

[AF]

Eric, Thanks for the info.... answers a couple questions. 1 - Can't do it with a table router. 2 - A bit exists that is able to cut the part out of the sheet and put the round over at the same time.

Is this something that a Shopbot or other small size CNC is capable of?

SP

It could be done with a template and round over bit with bearing like the days before CNCs when we could do everything with jigs and fixtures. It is a lost art I suppose, but a cheap $1 dollar template would be worth trying before investing in a CNC. Having traditional skills and CNC skills will cover pretty much any part you will need to make. Some industries use the CNC to make templates for traditional processing, so getting the template made would be even simpler if you have access to a CNC.

 

[rjssigns]

Double sided tape to hold the piece to the work table then build a fixture to guide a router. It would also require the use of a guide bushing in the router base. A tiny portion of a 1/4" round over bit would be used.

The purpose of the fixture would be to protect the top surface that can't be scratched and act as a guide.

Just thinking out loud here...you could use a router table. You'd need an inverted bearing guided bit. Like this: http://www.woodcraft.com/Product/82...le-router-bit-12sh-112od-38r-3764cl-34bd.aspx

 

[Eric H]

I would think about any cnc would be able to handle it. The only problem doing it this way is the material needs to be a consistent thickness if it is a little thicker or thinner in spots it will show. This is the type of bit I was talking about- http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/bit_groove.html. Doesn't necessarily need to be pointed but they don't generally extend past the radius, the flat bottom ones do. AM is right it could be done with some sort of jig by hand. Do you have other needs for a cnc?

 

[J Hill Designs]

cut the oval shape out of 1/2" MDF - tape down your piece to it, cover in transfer tape to protect, get a flush trim router bit with radius. Once set up you can blast through them pretty quickly.

 

[Team Valhalla]

All interesting and informative input - thanks for the responses!

SP

 

[bob]

Get a Veritas Cornering Tool set [~35.00] and do it by hand.

 

[Marlene]

that is a pretty cool tool bob. does it work on PVC?

 

[Eric H]

Get a Veritas Cornering Tool set [~35.00] and do it by hand.

400 blanks a year with that? Have fun.

 

[bob]

that is a pretty cool tool bob. does it work on PVC?

Probably work better since the material is homogenous and there's no annoying grain to catch or worry about. Moreover there's no tool speed to melt the material instead of cutting it.

400 blanks a year with that? Have fun.

Wow 400 in 365 days. That's a massive 1.1 a day, or figuring ~260 working days a year it comes to an equally intimidating 1.5 a day. Each with a perimeter of 40". You should be able to dress 40" of edge in seconds.

 

[Marlene]

good point bob about no speed/no melting the plastic. I want one of these and will track a set down, thanks for the info

 

[kiowaas]

Without going to a handheld router or CNC, a round over bit with a bearing can be mounted in a invert router table (think Duz-all) and then just tracking the part face down. No jigs, no muss, no fuss - you may burn a piece or three getting you feed rate down, though.

 

[Techman]

Stanley makes a similar tool as well.

 

[SignProPlus-Alex]

It could be done with cnc. Here is step-by-step.
1- cut all 400 blanks you will need 10 4x8 sheets of pvc. Cutting time 9 min per sheet. I am assuming you have vacuum table.
2- setup raised vacuum holding jig. http://www.woodweb.com/knowledge_base/Vacuum_Pod_Tips.html
3 - with bullnose bit cut all parts one-by-one. http://www.amanatool.com/51540-carbide-tipped-bullnose-5-64-radius-x-17-32-dia-x-1-2-x-1.html
4 - store them till you need them.
My calculation you will be done in 7-8 hours.

 

[fixtureman]

Eric, Thanks for the info.... answers a couple questions. 1 - Can't do it with a table router. 2 - A bit exists that is able to cut the part out of the sheet and put the round over at the same time.

Is this something that a Shopbot or other small size CNC is capable of?

SP

Yes it could be done on a Shopbot. I have a shopbot and do something like this for a customer.