Boring heads

[Alan Waddington 2Participant @alanwaddington2]

Posted by ega on 24/10/2018 23:46:07:

Posted by not done it yet on 24/10/2018 22:01:25:

Apart from the fact that the Rotabroach type of cutter has flutes for chip clearance it has the added advantage that it cuts closer to size and, further, a pilot is not necessary so that the resultant slug has no central hole.

A pilot isn’t necessary with a hole saw either, if mounted in a drill press or mill, infact you can even use them freehand without the pilot drill if you use some form of jig to centre.

[David Standing 1Participant @davidstanding1]

As the hole required is 100 mm dia and the material 25 mm deep, good luck to anyone using a hole saw for that!

[Ron LadenParticipant @ronladen17547]

Posted by JasonB on 25/10/2018 07:18:13:

Well that "cheap" import Soba that is in my picture above manages to cut holes for ball races that are a good fit.

Neil will be better able to comment on the power of an X2 but I'll stick an ARC boring head into the next size up SX2.7 later and see what it can do. SX2 certainly won't have the guts to turn a near 100mm holesaw let alone rotabroach with it's larger kerf but as the boring head allows a much smaller cut the load can be kept down.

Not sure where this 20rpm comes from, more like 130rpm for steel and 170 for aluminium with HSS so 50% or more increase for Carbide tooling.

Ron, is this to fit the "boiler" barrel of your traction engine?

 

Hi Jason, you dont miss a lot do you.. yes, the boiler is 4 inch 10swg alu tube with the firebox made up from 6 inch alu flat bar with a 25mm thick front plate.. I can imagine people going into shock and horror now, I know it breaks away from the conventional way but I wont explain my reasons here I will start a thread and explain there. Thinking about it a bit more, I doubt that 4 inch alu tube will be perfectly round so my tolerance of a couple of thou is probably an exaggeration, I would need to measure the tube and work out a size for fit.

Ron

Edited By Ron Laden on 25/10/2018 09:41:50

Edited By Ron Laden on 25/10/2018 09:48:23

[Simon Williams 3Participant @simonwilliams3]

Morning All,

My suggestion of needing to be able to run at 20 or 30 rpm comes from having done exactly the same job myself, using a Rong Fu drill mill. By the time I got to 75 mm diameter running the cutter at a "proper" speed I'd got all the chatter in the world going on, so reducing the speed significantly is one way of reducing this to give a good enough surface finish to hold that tolerance of a couple of thou. I just wanted the biggest hole I could cut in a steel flywheel as part of a home made wood chipper, I got to 100 mm dia eventually but it was on the absolute limit of my capabilities. I wasn't bothered about hole tolerance, it was a clearance hole for the chips to go through, but I did want it to look pretty. Incidentally I cut two of them, as the flywheel had to balance (approximately!)

The mill drill has its limitations, but it is big and heavy (for the size of machine) and it will run slowly with lots of torque. No offence to the SX machine, but I've got me doubts.

I forgot to note that the boring tool used in the head axially is a right handed tool, but the tool needed for the radial position is a left handed tool, as it cuts on the opposite edge.

I'm afraid I'm responsible for putting Ron off having a go. My apologies for being such a doubting Thomas, by all means have a go but approach with circumspection!

I've also drilled holes in one inch steel plate with a hole saw. They will do it, but we mounted the work on the table of a big vertical mill with flood coolant and went very slowly with frequent withdrawals. That was a 40 mm hole, not sure that much larger is viable as the saw is too flexible.

Best rgds Simon

[Ron LadenParticipant @ronladen17547]

Dont apologise Simon, I would rather know all the possible pitfalls than to go ahead and possibly damage the mill.

Ron

[Alan Waddington 2Participant @alanwaddington2]

Posted by David Standing 1 on 25/10/2018 08:54:12:

As the hole required is 100 mm dia and the material 25 mm deep, good luck to anyone using a hole saw for that!

Shouldn’t be a problem with a decent quality holesaw and patience, problem with ally is it clogs the teeth, so needs plenty of lube, parrafin or WD40. Best to peck at it too, or the heat build up nips the blade.

Have done a 75mm hole through the web of an RSJ using a cordless, whilst balancing on a step ladder……..now that was interesting

[JasonBModerator @jasonb]

Ron, as it is a throat plate will it actually be a hole of just a half circle cut out the top edge?

[Ron LadenParticipant @ronladen17547]

Posted by JasonB on 25/10/2018 10:08:15:

Ron, as it is a throat plate will it actually be a hole of just a half circle cut out the top edge?

Jason, sorry I dont know all the correct terminology and methods yet, I was planning on a hole with the boiler tube fitted the full 25mm depth. Is there a reason for the half circle which I am missing..?

[JasonBModerator @jasonb]

It is just a common way to do it with copper and steel boilers but all bets are off with yours!!

I only asked as I will do a similar cut to what you propose so if it were a half circle then that is what I would have tried.

[Ron LadenParticipant @ronladen17547]

Posted by JasonB on 25/10/2018 10:19:44:

It is just a common way to do it with copper and steel boilers but all bets are off with yours!!

I only asked as I will do a similar cut to what you propose so if it were a half circle then that is what I would have tried.

Really appreciate this Jason, I will be interested to know the results as if its possible I would like to give it a try.

Ron

Edited By Ron Laden on 25/10/2018 10:31:51

[Clive FosterParticipant @clivefoster55965]

Chip problem when going deep with hole saws is greatly alleviated if you drill a couple or four holes slightly overlapping the cut to give the chips somewhere to go. Maybe 1/4" diameter if doing big hole. Need somewhere below for the chips to go too. I've done 3" diameter in 20 mm material. Less than ideal but did the job. Went through halfway and flipped the part over.

Finished off with a boring head in a big Chester Lux style square column mill. VFD drive got the speed down low so it did the job fine but I'd not care to have gone much bigger as I'd have been pushing what the machine could do in normal operation. Really don't like pushing machines beyond their capacity and nursing a job through.

My boring head is a middling range affordable import type. Two gib screws and a central lock screw. Really prefers to operate with the dovetail slide covering both gib screws. Any further out and it all seems bit much for it to behave well. Can still do the job but you have to work at it.

When I had an 6" hole to do I popped it on a rotary table, chain drilled it and milled round using a normal cutter. Much better way of going about things once you have a rotary table. I left the centre piece in holding it with screws into the sacrificial base between job and table. Knocking out would have meant taking the job off and re-centering.

Clive.

Edited By Clive Foster on 25/10/2018 10:34:24

[JasonBModerator @jasonb]

Rather than waste a nice bit of 6082 25mm plate I found an old fingerplate which is some soft gummy ali but it will do for the purpose and it also made it easy to bandsaw out the waste before butting the two bits together.

Quick rough and ready free hand regrind of one of the tools supplied in this ARC set, it's the same head I'm using too and we are good to go.

As I have said before these variable speed benchtop mills and the vari speed lathes for that matter are better off run a bit faster with a slightly shallower cut than a big old industrial machine would typically use. So being aluminium and with a carbide tip I dialed up 500rpm. Cuts are 1mm off dia (0,5mm DOC) not the smoothest of feeds as I was only able to use one hand and could only add a drop of paraffin at the start. I have set the gibs as I do on my SOBA which is firm then I don't have to faff about loosening and then retightening each time a cut is put on.

 

 

Now the SX2.7 is a bit more rigid and has 750w rather than Rons SX2 at 500w so if he took off half that DOC it would not take too many passes to clean up the last 4mm of material left by stitch drilling with a 6mm drill 1mm inside finished diameter, could probably use quill lever to feed on the initial rough cuts.

 

 

Not much sign of chatter on the cut edge

 

 

Edited By JasonB on 25/10/2018 11:54:13

[egaParticipant @ega]

On the theme of hand-held hole saws:

[Paul KempParticipant @paulkemp46892]

Jason,

Doesn't look a lot wrong with that for Ron's purpose!

Ron,

Don't be put off by the nay sayers! Amuses me greatly sometimes when responses to a question prompt a sharp intake of breath and Nay lad, you'll not be doing that! There is usually a way of achieving what you need when you don't need an accuracy of 2/10 of a thou. It's nice to have the all singing all dancing professional kit but for the purposes of back yard engineering perfectly acceptable results can be achieved with less. As someone once said to me, "you can only wee with the willy you've got".

Paul.

[Ron LadenParticipant @ronladen17547]

Posted by JasonB on 25/10/2018 11:48:32:

Rather than waste a nice bit of 6082 25mm plate I found an old fingerplate which is some soft gummy ali but it will do for the purpose and it also made it easy to bandsaw out the waste before butting the two bits together.

Quick rough and ready free hand regrind of one of the tools supplied in this ARC set, it's the same head I'm using too and we are good to go.

As I have said before these variable speed benchtop mills and the vari speed lathes for that matter are better off run a bit faster with a slightly shallower cut than a big old industrial machine would typically use. So being aluminium and with a carbide tip I dialed up 500rpm. Cuts are 1mm off dia (0,5mm DOC) not the smoothest of feeds as I was only able to use one hand and could only add a drop of paraffin at the start. I have set the gibs as I do on my SOBA which is firm then I don't have to faff about loosening and then retightening each time a cut is put on.

Now the SX2.7 is a bit more rigid and has 750w rather than Rons SX2 at 500w so if he took off half that DOC it would not take too many passes to clean up the last 4mm of material left by stitch drilling with a 6mm drill 1mm inside finished diameter, could probably use quill lever to feed on the initial rough cuts.

Not much sign of chatter on the cut edge

Edited By JasonB on 25/10/2018 11:54:13

Thanks Jason for taking the time and effort to do this trial it certainly looked like a success. I will order the tooling from ARC and give it a go. Like you suggest if I take light cuts it should be ok, I wont rush it and it will be good to be able to do it myself plus I will have a boring head set for other jobs. I will start a thread later on the traction engine and post a sketch of how I am considering the boiler/firebox.

Thanks again, really appreciated

Ron

[Alan VosParticipant @alanvos39612]

Posted by Ron Laden on 24/10/2018 19:19:20:

I hope ******* is not what I think it may be Alan, but I will assume it isnt.

What I had in mind is described by Channel 4 as "relatively inoffensive and its inclusion, even in a programme watched by large numbers of children, would be unlikely to offend most viewers."

Regarding the original subject, if needed, I would have a go at boring 100mm in aluminium on my SX2P. Nice sharp HSS tool, small cuts, WD40. And, as noted by others, being cautious about the duty cycle to protect the motor. Assuming a chain drilled starter hole, the bulk of the lumps that would cause an interrupted cut could be knocked off using a normal milling cutter and manual X-Y manipulation, or even a large round file.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Alan Vos on 25/10/2018 18:31:41:

Posted by Ron Laden on 24/10/2018 19:19:20:

I hope ******* is not what I think it may be Alan, but I will assume it isnt.

What I had in mind is described by Channel 4 as "relatively inoffensive and its inclusion, even in a programme watched by large numbers of children, would be unlikely to offend most viewers."

.

What I find very strange is that Channel 4's webpage on this topic appears to be freely accessible to the previously innocent eye:

[Warning: those of a sensitive disposition should probably not follow this link] : **LINK**

https://www.channel4.com/producers-handbook/ofcom-broadcasting-code/protecting-under-18s-and-harm-and-offence/offensive-language

MichaelG.

[Howard LewisParticipant @howardlewis46836]

Recently, I need a 2 inch diameter hole in some 1/2 inch thick Aluminium.

Admittedly, it was done in the lathe with a 1.5 hp motor, at 90 rpm, but I used a 1.75 inch diameter hole saw. White Spirit or Neatcut as lubricant, and frequent withdrawal to clear the swarf.. The hole was then bored to size, with a CCMT0604 tip in 8mm dia boring tool. Cuts were 0.020" maximum, with final cuts being "spring cuts".

The holesaw may tax your 500 W motor, but many pistol drills had no larger a motor, years ago, and they drove holesaws. Don't force it, ( keep the cuts shallow) lubricate, and clear the swarf frequently. To arrive at finish size, even from 1.75 inches, took a little time, but a lot less than trying to take umpteen 0.020" cuts from 1/2".

Look at the work that has been produced on ML7s; apparently beyond its capabilities!

As the saying goes "Slowly, slowly catchee monkey" Most of us are on a hobby, not piecework!

Howard

[Ron LadenParticipant @ronladen17547]

Just about to order a boring head set from ARC, comes with a carbide tool set, would anyone know if the tips come sharpened. I dont have a green wheel yet and when I received a set of tipped tools for the mini lathe (not from ARC) they were cut to shape but not blunt.

Ron

[John HaineParticipant @johnhaine32865]

Some time back I had to cut a 4" hole in 1/8 aluminium plate for a flue. I used a boring head in my VMB and made a trammel cutter with a length of 1/2" silver steel going through the transverse hole and a 1/8" HSS bit mounted in a cross-hole near the end of the bar and ground to a narrow oarting-tool like edge at the end with lots of side clearance. Ran the machine at lowest speed and very slow feed, went through OK but I did have a couple of jams.

[Neil WyattModerator @neilwyatt]

Posted by Ron Laden on 26/10/2018 10:46:12:

Just about to order a boring head set from ARC, comes with a carbide tool set, would anyone know if the tips come sharpened. I dont have a green wheel yet and when I received a set of tipped tools for the mini lathe (not from ARC) they were cut to shape but not blunt.

Ron

I believe they are, but call Arc to check.

It's often necessary to relieve the front face anyway if you want to use them in smaller holes.

Neil

[JasonBModerator @jasonb]

They do come sharpened but none will be ground correctly for use in the side holes. You may want to just touch them up with a diamond slip but will need to grind then for use in the side.

[Ron LadenParticipant @ronladen17547]

Thanks guys

Ron

[egaParticipant @ega]

Posted by Alan Waddington 2 on 25/10/2018 08:36:07:

Posted by ega on 24/10/2018 23:46:07:

Posted by not done it yet on 24/10/2018 22:01:25:

Apart from the fact that the Rotabroach type of cutter has flutes for chip clearance it has the added advantage that it cuts closer to size and, further, a pilot is not necessary so that the resultant slug has no central hole.

A pilot isn’t necessary with a hole saw either, if mounted in a drill press or mill, infact you can even use them freehand without the pilot drill if you use some form of jig to centre.

Thanks for the tip about pilotless centre drills. I tried this today with a 74mm hole saw on some 3mm plastics sheet; undemanding material but I was impressed by the ease of the operation.

[egaParticipant @ega]

PS I meant to say pilotless *hole saws* (and the one in question was actually 70mm diameter.

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