Drilling a massive hole in 40mm plate?

[astro_al]

Hi guys, anyone know if there is a gizmo out there which will 'drill' a large hole in 40mm plate?

The plate is too big (about 2' by 3') to go on the lathe or be rotated on the mill table. But I do have a couple of drill presses that'll reach the centre happily.

I need to put about a 210mm (8 1/4") hole in the centre of the plate. Is there something I can mount in the drill to do it? A single arm flycutter or something?

Cheers, Al.

 

[piman]

Hello Al,

a fly cutter will not cut to 40mm depth. You could get a hole saw but it depends on how accurate and what finish you need. Would flame cutting not be practical?

Alec

 

[Welderpaul]

Depends what its for - either flame cut yourself, or alternativly, buy the plate from a profilers, ready cut to required sizes with the hole.
A large engineering place will be able to machine the hole, but it is likely to cost more than the profile option.
A hole saw of that size won't cut 40mm plate.

What you making?

 

[scott0031]

Hi Al,

I have no idea what machines you actually have at your disposal, but i think its safe to say the pillar drill method is out due to loadings and depth you need, pillar drill are just not designed for such work. I think even a hole saw will be awfully difficult due to the overall cutting area/ power of machine etc etc. Unless you have a monster of a machine to hand.

If its only a crude hole you need, can you not reach the circumference of hole hole on the mill? If you can reach it you could mill it out but by bit. Do a straight slot to gain some space then plunge feed to the marked circumference of the hole, rinse repeat. Even if you can manage to do that its a hell of a lot of time and work to complete and will be expensive on cutters to complete.

what Mill have you got Al?


The only other realistic options i can think of is flame, water, plasma etc etc. Failing that find a friendly cnc shop with the right tools, a decent machining centre with the right tooling would plough that out pretty fast.



Kind regards,


Scott

 

[Shox Dr]

Take and get it Laser/flame or water cut. Any type of machining will take an age, unless you have a massive setup

 

[Drains]

If it's 2' wide then it's 1' to the centre. Is your mill throat not deep enough to take that? I'd have thought you could rough it out with o/a then trim with a big ole fly cutter.

 

[stormin]

You need a trepanning tool. More commonly available for wood but also available for metal. They're like a cross between a boring head and flycutter, doing the job of a holesaw with a single cutting tool edge.

 

[500e]

www.precisionprofiles.co.uk/

http://www.barrettsteel.com/Products-Services/Services.aspx

 

[Hitch]

Do you already have the plate?

Free issue it to Pegasus Profiles, not far from you....

what's the accuracy got to be like?

 

[astro_al]

Thanks guys. I'll try to cover everything:

Yes, I already have the plate.

I have a geared head drill that is beefy enough for the job, but it sounds like a lost cause on the tooling front. The mill is a little old series 1 bridgeport, I'm pretty sure it lacks the throat to access parts of the hole to be cut (the plate has some funny curved end bits sticking out - should have said before).

I need to stick a solid steel cylinder of 210mm dia through the hole and weld it in place (for a tool build).

My plasma will cut it, but I was hoping for a nice accurate machined-type hole. With thick-ish steel like that its easy to get the 'exit wound' pretty off line, what with the natural kerf angle plus any inconsistencies in the torch angle while you're cutting.

I guess thats really my only option. Its at times like this I wish I'd got round to that damn CNC plasma build thats been floating around for a couple of years.

Stormin' - you got a link to a tool that'll do the job? I can'tfind anything.

Ta, Al.

 

[scott0031]

various different models of the series 1 so a bit hard to define which you have. That said don't forget you do have a ram head on that machine and the head also swivels, you can actually get some pretty large work pieces on a Bridgeport with some Ingenuity and manipulation. Its still a lot of work taking all that material out though how ever you machine it manually.


Another option could be the lathe if its big enough and you have 12" from saddle to center height (assuming the hole is in the centre) you will need the fortune of having saddle that has T slot facilities. Two angle plates mounted on the saddle, job clamped to angle plates and drill and bore from the head stock. Use a 4 jaw to gain the offset for the boring bar. If you cant get enough offset for the tool that way, make a tool with a pre-offset so you can attain the size you need.

How big is your lathe?


Kind regards,


Scott

 

[jugs]

This is a trepanning tool

http://www.btahellerinc.com/trepanning.php

megga money

You should be able to bore it on the B'port as long as the head & table are locked solid & you take light cuts, but easier to find a shop with a CNC mill,

 

[scott0031]

Thinking again here, if all else fails with the suggestions/methods and you find you cant physically get it in any machine and have to look at out sourcing. I think i would be tempted to get the core out myself to leave less work for someone else. Even if it will fit in one of your machines getting that core out is the key preventing hours of machining.

Think about chain drilling it as tight as you dare, then getting the plasma and nipping that core out. That should eliminate the problems with the plasma you mentioned and wont leave masses of hard slag to kill cutting tools, plus any hard slag if any will be easy to remove as it will only be on the thin walls between the chain drilling.


Its a thought.



Kind regards,


Scott

 

[hotrodder]

I need to stick a solid steel cylinder of 210mm dia through the hole and weld it in place (for a tool build).

Could you not weld a chunk of bar to each side? Just throwing an idea out there i'm wondering about turning a centre register on the end of the bars and a smaller, more managable sized hole in the plate

 

[Engineer]

Is the part made out of a material that cannot be water jetted or laser cut or is a greater degree of accuracy required? For greater accuracy EDM is worth looking out, but this will be more costly than the other options.

 

[Drains]

If you go the plasma roughing option, watch out for the hard nitrided edge plasma can leave (I doubted this existed until experience indicated otherwise).

 

[TechnicAl]

Could you not weld a chunk of bar to each side? Just throwing an idea out there i'm wondering about turning a centre register on the end of the bars and a smaller, more managable sized hole in the plate

Thats what I was thinking (great minds etc)

You could chamfer the edges of the bar and do a partial pen joint. The advantage is that the 210mm bar going through a 50mm plate is a classic weld crack test.
You will need LH rods/wire (assuming its MS) and plenty of preheat. You will also need to stagger the welds

 

[Shox Dr]

LH* (Left hand) Do you buy them from a same shop that sells Glass hammers.


Use of Abbreviations





*Low Hydrogen

 

[Hitch]

If you go the plasma roughing option, watch out for the hard intruded edge plasma can leave (I doubted this existed until experience indicated otherwise).

Quite right Si.

We regularly do a job which involves maching 113 (or something like that) holes through 20mm plate.

We usually get them in flame cut, then tidy them up. the very slight inconsistencies in shape (even from cnc) seem to make the tool bounce off. Could just be our machinest mind.

I can see a nice chunky bit of solid bar, with a replaceable tipped turning tool clacked on it and a fitting that will fit in a mill/drill..... Cut it out 4-5mm smaller and trepan it out to the finished size.
The only trouble with doing it like that, youd have to remove the majority first by another method, unless you had a cutter wider than the holder- probably not practicle on 40mm thiick material....

This is the sort of trepanner i had in mind....

 

[Welderpaul]

Am i missing something - if your welding round section into the hole, why not just burn it out?? No need for mega accuracy/CNC (Computer numerically controlled)