I need advice on making non- standard diameter holes

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scattermaster

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Hello,
I have a chance to do some actual money making work!
I need to make some steel plates, about 5" square and 1/8" thick. They all have a number of holes that I have to cut.
Diameters are: .830" - .355" - .595" - and .435".
I don't think end mills come in these sizes.
My thought was to drill as close as I can and finish up with a boring tool, but that seems too time consuming.
Looking for ideas.
thx,
Jim
edit, tolerance is + or - .005"
 
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Boring head would be needed to get those size holes and the accuracy level unless you can do it CNC. If doing multiple pieces, jig them up for alignment and drill close to target and then bore the same holes in a group.
 
Some of those sizes are very close to whole millimeter sizes. Depending on the tolerances specified for the holes, you might be able to use metric size cutters.
 
Forty Niner,
Looks like you're right.
my tolerance is =/- .005" (.127mm)
.830" = 21.082mm
.595" = 15.113mm
.435" = 11.049mm
.355" = 9.017mm
SO,
instead of drilling and then using end mills, would it be better to use annular cutters for the larger holes?
 
Will the annulars hold the + or - .005 tolerance ? You could drill and ream to finish size also . Odd ball reamers are plentiful .
 
scattermaster said:
Diameters are: .830" - .355" - .595" - and .435".
I don't think end mills come in these sizes.
My thought was to drill as close as I can and finish up with a boring tool, but that seems too time consuming.
Click to expand...
End mills can, but custom made can be expensive. However, regular drill bits come close enough. What I would do is cut the plates about 1/8" oversized, then weld them all together stacked up. Drill ONE hole for each size, then use an adjustable reamer to get closer to spec. Then just mill off the weld, knock off the sharp edges and you're done.
 
If the hole they make is acceptable, drill bits can be re-sized a little by grinding the flutes with an appropriate grinder. You'll have to test or undersize the drill a bit because it's a drill, but it's one way to do it. It's jobs like the one you're doing that make a Deckel clone or similar pay for itself. You'll always have the right size, and your tools will always be sharp.
 
If I read your tolerance correctly the holes can be up to .005 undersize but not oversize. For example the .830 hole can range in size from .825 to .830. Drills tend to drill a slightly oversize hole. Using the metric drills should give you a hole within spec. You can also buy end mills in those sizes.
 
Since you don't have a CNC machine, if there are enough parts to justify buying proper size reamers, then that is the route to go. Otherwise it is a ''No Bid''

Personally I would have them laser cut, we would not do these in-house for our own stuff. SendCutSend is my go to vendor for stuff like this. https://sendcutsend.com/
 
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