Standard Radius sizes

[CdoubleZ]

I am wondering if anyone has a resource for Standard radius callouts.

That is, I would like to specify a radius diameter for inside cuts of a plate for example (lightening holes) to enable the cutter to use the same drill bit for cost effectiveness.

Does anyone know where can access this information?

 

[MintJulep]

Tool supply catalog.

 

[Heckler]

A standard radius would be the radius of any endmill cutter....1/8, 1/4, 3/8.....etc. I would just make the radius a two place dimension to give the machinist some flexibility. Also, check the Machinery's Handbook for standard drill bit sizes or do a search on the web.

Best Regards,

Heckler
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[ctopher]

Machinery handbook. Radii can be anything. If you mean fillets, look at the tool radius.

Chris
Systems Analyst, I.S.
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[MadMango]

If you want to give your machinists flexibility, modify the radius callouts with either MIN or MAX.

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[ctopher]

I agree. I always use MIN or MAX, unless the design needs otherwise.

Chris
Systems Analyst, I.S.
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[ajack1]

General rule of thumb the bigger the better. If you are machining a plate say three inches thick no one will thank you much for putting a 1/8 rad in the corner. Have you ever tried buying a ¼ cutter 3 inches long?

Also if you are looking to CNC machine these a radius bigger than the cutter is best as you then have a cutter path and it does not “slam” into the corners.

 

[CdoubleZ]

ok, well the plate is 1/4" thick...

its somewhat square, and the cut is somewhat square as well... a fillet on the order of .100 on the inside of the lightening cut, give or take, looks ok from a design standpoint.

so should i specify .12 min as the dimension? (1/8 drill)

again, im after low cost, ease of manufacturabilty here.

 

[ewh]

R.12 would be a 1/4 drill, and sounds reasonable given your matl thickness.

 

[CdoubleZ]

oh yeah woops... ok

 

[wgchere]

If you are after the lowest cost, consider makeing them round holes, an endmill diameter ±.020 and a big surface roughness callout (maybe 125 RMS) so the machinist can just "plunge" the endmill--in and out.

 

[ajack1]

If they really don’t matter then flame, laser or water jet cutting would probably be cheaper. Well it would be cheaper but you might need to outsource so might not be, if that makes sense.

 

[alexit]

If plate is 1/4" thick, I would try to keep any inside corners at least 1/4" radius (2x thickness) to keep machinist happy...unless you are planning to Wire EDM, Water Jet, Laser or otherwise cut the plate instead of machining it.

 

[CdoubleZ]

so... .25 min on the drawing?

this way if it cuts in excess of .25, itll be ok?

 

[ctopher]

It also depends on what the holes are used for. If the hole in the plate is used for a LED or connector or ??, or is covered with some time of label, I wouldn't use a R .25. The size depends on you and your design.

Chris
Systems Analyst, I.S.
SolidWorks/PDMWorks 05
AutoCAD 06
ctopher's home site (updated 06-21-05)
FAQ559-1100
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[MikeHalloran]

If the plate is machined on a CNC mill, any radius larger than that of a reasonable size cutter is no big deal. CNC mills can orbit a cutter to produce arbitrarily sized holes.



Mike Halloran
Pembroke Pines, FL, USA

 

[drawoh]

CdoubleZ,

Your standard radius probably should be bigger than the machinist's cutter. If they are writing a CNC program to fabricate your part, they do not want to pause the cutting tool. They want to move the tool around in an arc at a constant velocity.

If I want them to use a 1/2" cutter, I specify a radius of 0.35".

If they are machining on a manual mill, then the radius is your cutter's radius.

JHG