Imperial sized drill bits

[memzey]

Hi gang,

I'm looking for a 3/8" sized drill bit for drilling in mild steel. I want a snug fit with a 3/8" * 3/4" BSW bolt so accuracy is important to me. Can someone recommend a decent supplier for my needs please?

TIA

memzey

 

[woodpig]

I'm not sure what you're expecting but most bolts can be quite a bit under the stated size. A 3/8" bolt in a 3/8" hole may not be as snug as you put it as you think. As for imperial drill bits lots of places sell them just not the big box stores. You could try Cromwell tools, Buck & Hickman, Chronos, Tracy tools or any number of online sellers.

Edit:

There's a branch of Cromwells in Luton. You don't need an account, just pop in. If they don't have what you want in stock it's normally available next day.

https://www.cromwell.co.uk/branches

There's also a branch of Buck & Hickman in Luton.

 

[marcros]

i use http://www.ukdrills.com

not had a problem with accuracy on those that I have used.

 

[Eric The Viking]

My Presto "Counsellor" says that the clearance hole for 3/8" Whit is actually 9.70mm,
so how snug is "snug"

10mm is 0.3mm float, or 9.5mm might be drilled a bit loose...

You can probably find 9.7 as a 2nd series jobber drill.

In terms of good quality, Dormer drills on ebay are hard to beat.

 

[woodpig]

Couple of quid inc postage:

http://www.chronos.ltd.uk/acatalog/Engi ... s_172.html

Or if you want metric, ie 9.5, 9.6 etc:

http://www.chronos.ltd.uk/acatalog/Engi ... s_171.html

 

[memzey]

Thanks guys. As far as I can tell the bolts are 9.32mm in diameter.

I'd want something as close to that as possible as what I want to use it for requires extremely close tolerances.

 

[RossJarvis]

Without knowing what you're doing it's hard to know how to comment, however you may want to put a "sleeve" in instead. Use a piece of tube to the correct outside dimension with a smaller screw inside for clamping. I'd always be very wary of using the outside of any screw as a dimensioning feature.

 

[memzey]

I do have the option of using 1/4" roll pins/metal dowels to locate the item being bolted down but I don't have an easy way of locating them accurately.

 

[CHJ]

I do have the option of using 1/4" roll pins/metal dowels to locate the item being bolted down but I don't have an easy way of locating them accurately.

As long as one face of assembly is accessible to drill and surface hole in finished item is not a problem then location accuracy of 'Location pins' is immaterial.

Clamp together in correct location, drill through both pieces in suitable location, if best fit required ream to finished size.

Fixing bolts should then be in clearance holes with just head/washers in contact.

 

[memzey]

Thanks Chas. Do you have any suggestions as to where I can find the right roll pins or dowels for this? I've never really done this kind of thing before (not that you probably couldn't tell).

 

[CHJ]

Thanks Chas. Do you have any suggestions as to where I can find the right roll pins or dowels for this? ...

http://www.glrkennions.co.uk/split-roll-taper-pins.html

 

[memzey]

Brilliant stuff Chas. That's a great site but they don't list 1/4" pins unfortunately. Any other suggestions? I might give them a call anyway and see if they can source a couple for me.

 

[MusicMan]

The size of location pin is not critical. You can probably find them on eBay. A solid dowel is also fine.

To make an accurate drill hole, first drill slightly undersize then put the final drill through slowly (but at the right rotation speed). As CHJ says, you might want to get a reamer to match the location pins and finish off with that.

Keith

 

[woodpig]

Loads on eBay.

http://www.ebay.co.uk/itm/Dowel-Pins-Ha ... QVvQHVjZ8w

I buy most of my fasteners on there these days.

 

[MCB]

Hi gang,

I'm looking for a 3/8" sized drill bit for drilling in mild steel. I want a snug fit with a 3/8" * 3/4" BSW bolt so accuracy is important to me. Can someone recommend a decent supplier for my needs please?

TIA

memzey

It's a little too late in the evening to look now but I think I may have a spare 3/8 drill bit

I think I also have 3/8 hand reamer(s) and BSW taps and dies

I note that you are in St. Albans - I travel along the A414 almost every day from Hertford to Hemel Hempstead so could meet you locally if that would help.

Send me a message off list with your email address and landline telephone number and I'll contact you

With best wishes.

MC Black

 

[memzey]

Top man MCB! I will PM you with my email. Even if it doesn't work out it would be nice to just know another woodworker close by. There are no woodworking clubs in the area which is a bit of a shame.

I did get some 1/4" spring pins from eBay but they are actually a bit bigger than 1/4". I assume they compress down to final diameter once hammered into their holes? Is that how they are supposed to work? Once I've completed my mangling I'll post some pictures up of what I've been trying to do.