How to deburr cross holes inside a bore?

[extropic]

I have the Noga set. I think it's OK for a few holes and softish materials. Too fiddly for a bunch of holes in steel. You didn't specify your workpiece material or quantity, so . . . YMMV.

Given that the tapped holes are very close to one end of the workpiece, I recommend using a ball end carbide bur in a hand chuck or rotary tool.
Very effective and not expensive.

McMaster-Carr

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[RJSakowski]

I ran across that problem drilling .009" cross holes in Delrin, Delrin is notorious for leaving a a tiny string at the end of a machining operation We solved the problem by inserting a plug in the main bore before drilling the cross hole. With the cross hoe drilled, we pulled the plug, leaving a clean exit of the cross hole.

 

[dml66]

3mm to 5.5mm. Never seen a 55mm one

Typo

 

[dml66]

I have the Noga set. I think it's OK for a few holes and softish materials. Too fiddly for a bunch of holes in steel. You didn't specify your workpiece material or quantity, so . . . YMMV.

Given that the tapped holes are very close to one end of the workpiece, I recommend using a ball end carbide bur in a hand chuck or rotary tool.
Very effective and not expensive.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

Material will be 12L14. The part is a one-off, if the Noga doesn't work out, I'll try ball end carbide tool. Thank you.

 

[dml66]

I ran across that problem drilling .009" cross holes in Delrin, Delrin is notorious for leaving a a tiny string at the end of a machining operation We solved the problem by inserting a plug in the main bore before drilling the cross hole. With the cross hoe drilled, we pulled the plug, leaving a clean exit of the cross hole.

I thought about plugging it with aluminum or brass, then I got concerned about having the plug jam in the bore and causing more trouble. Overthinking things is one of my strong suits .

 

[dml66]

Good advice, thank you. The RC1000 Noga has a range of 3mm-55mm, the #6 hole I'm working with is 0.138" or about 3.5mm, I should be good to go.

Hmmm, upon further reflection, 0.138" for 6-32 is the major diameter. The tap drill charts says a #32 drill in steel, that's 2.95mm . I may have to use a #31 drill, 3.01mm, or move to 8-32 thumb screws; either way I can make it work. Test holes are in my future.

 

[GeneT45]

You can plug with a hardwood dowel as well. Also, drilling close to size and then finishing with a drill that removes only a small amount of metal will help reduce the burr. Similarly reaming will nearly eliminate it.

GsT

 

[Eddyde]

Drill and tap the cross hole first, fill them with sacrificial screws then bore the axial hole. Use screws of similar hardness to the work, anneal if necessary.
Drilling the holes slightly undersize and reaming them to finish size afterward, can also work well.

 

[Eddyde]

Aside, I noticed in your drawing, the part shows two nylon tipped thumb screws directly opposite each other, presumably to grip a shaft to prevent rotation or sliding? If so, having the screws 180 degrees apart may not be the best configuration. 60 to 90 degrees apart is considered much better for such an application. This is because when the screws are directly opposite each other, there are the only two points of contact on the shaft, basically pushing against each other. When the screws are offset, they work together forcing the shaft against the wall of the bore giving three points of contact, and over a wider area where the shaft meets the bore. That's why the set-screws are offset not opposite on motor pulleys, gears etc.
Of course this may not apply if there are other factors to consider or be necessary, for light duty applications.

 

[Janderso]

Noga Reversible countersink deburring tool will do that...

View attachment 479487

Here is an evilbay listing for one...

1PC NOGA RC1000 RC2000 Mini / Medium Reversible Countersink Deburring tool | eBay

Model: Mini REVERSIBLE - RC1000. Type: countersinks deburring tool. Very fine tool for deburring both back and front side of holes. For deburring both back and front side of holes. Range 3-5.5mm. Range 5-10mm.

www.ebay.co.uk

I’ve been thinking about buying a set.