4.3 mm holes, 20 mm deep

[Chaz]

I need to do a set of 4.3 and 5.3 mm holes, at least 20mm deep.

I can drill these but will need to buy specific drill bits which may never get used again (around £15 each, carbide).

I could interpolate, problem is that a 3 or 4mm endmill typically only has a flute length of around 10mm max. There would likely be long reach endmills, will have to source.

Accuracy needs to be fairly good, how would you do this?

[EddyCurrent]

Those are about the size of a No4 and No18 drill if these are cheaper and accurate enough.

[Chaz]

Those are about the size of a No4 and No18 drill if these are cheaper and accurate enough.

Thanks, ive not seen those sizes before, checking prices.

Any idea who sells them in the UK?

[Lee Roberts]

So your going to be doing some tapping?

I would just spot drill (good them osborn/europa), then open them up as normal i.e jobber/twist drill bit, I've been using these Heller HSS German made bits pretty much exclusively recently without fail.

They do HSS-R and HSS-G versions, R is for non alloyed steels and G is aimed at alloyed, the G have a 135 degree split point for optimum centering and dimensional accuracy.

You can find them all over eBay if you search, I've even got their 15 and 20mm "black smith" type to open up clearance holes for my leadscrews...they worked sweet as a nut!

I wouldn't go anything less than the 4.3 you need, use the 4.3 for the 5.3 as well so you've got a nice pilot hole you can then open up, use plenty of cutting oil and take your time, dont forget to give the holes a small chamfer to help the tap locate :)

[Chaz]

So your going to be doing some tapping?

I would just spot drill (good them osborn/europa), then open them up as normal i.e jobber/twist drill bit, I've been using these Heller HSS German made bits pretty much exclusively recently without fail.

They do HSS-R and HSS-G versions, R is for non alloyed steels and G is aimed at alloyed, the G have a 135 degree split point for optimum centering and dimensional accuracy.

You can find them all over eBay if you search, I've even got their 15 and 20mm "black smith" type to open up clearance holes for my leadscrews...they worked sweet as a nut!

I wouldn't go anything less than the 4.3 you need, use the 4.3 for the 5.3 as well so you've got a nice pilot hole you can then open up, use plenty of cutting oil and take your time, dont forget to give the holes a small chamfer to help the tap locate :)

Thanks.

Phantom Drills came back and offered this:-

Phantom drill 11.770

They are cheaper than carbide, around £5 each. This was based on my requirement to do 'high speed' drilling due to limited low speed torque with the Chinese spindle.

This wont be tapped, its a through hole for a bolt.

[Lee Roberts]

This wont be tapped, its a through hole for a bolt.

Ok so the .3 is putting you in the middle of standard and close fit, what I've linked to should give you what you need for a through/clearance hole of fairly good accuracy surely?

[Chaz]

Ok so the .3 is putting you in the middle of standard and close fit, what I've linked to should give you what you need for a through/clearance hole of fairly good accuracy surely?

Yep, exactly. Ill order those drill bits, seems good value for money and keep for future if I ever need to do similar again.

[Lee Roberts]

Yep, exactly. Ill order those drill bits, seems good value for money and keep for future if I ever need to do similar again.

Cool, if you look I think you can just buy 1 bit at a time for 99p all in or something from another seller, saves buying a box of 10.

I'll confirm what I've got if you want and send you?

[EddyCurrent]

Number Drill set; http://www.ebay.co.uk/itm/RDGTOOLS-6...EAAOSwx~JWFOOB

[Chaz]

Cool, if you look I think you can just buy 1 bit at a time for 99p all in or something from another seller, saves buying a box of 10.

I'll confirm what I've got if you want and send you?

Sure, thanks, happy to pay.