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Boring heads

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John Reese01/11/2018 02:39:15
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I would suggest making the initial hole 55 to 60 mm., just large enough to pass the boring head with the tool sticking out a bit. Getting that initial hole made will probably e the most demanding part of the job in terms of torque. Once you are actually boring you can vary the depth of cut to stay within the limits of the motor.

JasonB01/11/2018 07:06:45
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Posted by John Reese on 01/11/2018 02:39:15:

I would suggest making the initial hole 55 to 60 mm., just large enough to pass the boring head with the tool sticking out a bit. Getting that initial hole made will probably e the most demanding part of the job in terms of torque. Once you are actually boring you can vary the depth of cut to stay within the limits of the motor.

Why will the initial hole be the most demanding part of the job?

Go back to the first page where several of us suggested stitch drilling out the waste which only requires a 6mm drill bit and even the SX2P won't baulk at that.

If the holes are drilled on a 92mm PCD that will leave the mimimum amount of metal to be removed with the boring head so it won't take long if done in shallow cuts of about 0.25mm as suggested earlier.

As for adjusting the head when upcutting, once the cut is complete and the tool above the work move the work, wind on the next cut, lower the tool and then reposition the work back on ctr using the handwheel scale and then take the next cut simples.

J

Ron Laden01/11/2018 08:41:24
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Thanks guys, I,ve had a good nights sleep and calmed down, sorry about my bit of a rant last evening I was just annoyed when I saw the tooling.

Anyway I have started the chain drilling to remove the bulk and I have found that one of the boring tools is not to badly shaped and sharpened (well to my inexperienced eyes anyway) I will touch it up with the diamond slip and it should be ready to go. I am going to try with the bit on the underside and bore down from the top, dont know how that will work out but I will see. The tool is one of the shorter ones and a bit chunky which I thought would be better than trying with one of the lighter duty ones. Light cuts and feed and I,m hoping the SX2 will cope, will let you know how I get on, thanks for all the advice guys.

Ron

Ron Laden01/11/2018 10:06:56
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Chain drilling done, thought I would be clever and chain drill with a 10mm cutter, did the first hole and then came to my senses and changed to the 6mm drill bit.

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JasonB01/11/2018 10:23:10
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Ron if you are trying one of the supplied tools make sure the back edge does not rub on the cut surface.

Ron Laden01/11/2018 11:02:17
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Posted by JasonB on 01/11/2018 10:23:10:

Ron if you are trying one of the supplied tools make sure the back edge does not rub on the cut surface.

Thanks Jason, I think it would have cleared but I relieved it a bit anyway. Pics below show the tool I am going to try and the way it will be mounted, dont know if it will work but worth a try.

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Emgee01/11/2018 12:03:53
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Ron

I think you may need to rotate the tool 90 degrees so the face of the tip is cutting.

Emgee

JasonB01/11/2018 12:09:35
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Edge on will be OK for light cuts I have used them that way when machining the outside of a part.

JasonB01/11/2018 12:19:47
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looks like it will just clear but not sure what the finish will be like as it is slightly negative rake

rons head.jpg

larry phelan 101/11/2018 13:15:44
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For holes that size,I chain drill and then clean up as much of the points left using a file. This makes it much easier on whatever cutter you use next. Would not like to try a hole that size using a boring head,sounds like a job for the lathe.

Ron Laden01/11/2018 13:37:24
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Posted by JasonB on 01/11/2018 12:19:47:

looks like it will just clear but not sure what the finish will be like as it is slightly negative rake

rons head.jpg

Thanks Jason, as you know I have no means of adjusting that at the moment but I am going to get a green wheel on order

Ron

Simon Williams 301/11/2018 16:45:43
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(Don't tell anyone I was mad enough to suggest this, but a diamond disc in the angle grinder will shape the tungsten carbide tool.)

It's a bit rough and ready and will need stoning up with a diamond file afterwards, but it can be done.

Keep up the good work, thanks for the photo's

Simon

Ron Laden01/11/2018 19:14:22
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Success, it went really well with no issues at all, I am really pleased and enjoyed doing it.

I must admit I was nervous though having not done it before and a largish hole in 25mm material, I was worried that it may push the mill too far but there was none of it. I would go as far as saying that the mill coped with it easily, there was no worrying sounds and not once did the mill seem laboured, no chatter or slowing or hesitation.

I did take it steady though, started with 0.125mm cuts until I got past the worst of the chain drilling and then used 0.250mm cuts from there on. I did try a 0.500mm cut and again no issues but stuck with the smaller cuts and a finishing cut to complete. Ran the mill at 550rpm, I know they say that the mini-mills power goes up and down with the revs but at 500rpm it obviously had enough. Pleased with the finish too, the carbide tool cut really well.

Thanks for all the help guys but I really do need to say a big thank you to Jason, he has helped me no end and his advice encouraged me to have a go when there was question marks raised over trying this on a mini.

Thanks

Ron

dsc06192.jpg

 

 

 

 

Edited By Ron Laden on 01/11/2018 19:26:22

Emgee01/11/2018 19:34:21
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Well done Ron, hole finish looks good.

Emgee

JasonB01/11/2018 20:36:32
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Can't get much better than thatthumbs up

Neil Wyatt01/11/2018 20:48:59
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Posted by Ron Laden on 01/11/2018 13:37:24:
Posted by JasonB on 01/11/2018 12:19:47:

looks like it will just clear but not sure what the finish will be like as it is slightly negative rake

rons head.jpg

Thanks Jason, as you know I have no means of adjusting that at the moment but I am going to get a green wheel on order

Ron

Isn't the rake angle of the vertical edge more important?

Martin Shaw 101/11/2018 21:23:22
118 forum posts
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Hi Ron

That's pretty impressive, I'm not at all certain I would have undertaken that, but it has undoubtedly worked well. Some food for thought here.

Martin

John Reese01/11/2018 21:52:47
847 forum posts

I am very impressed.

John

Ron Laden02/11/2018 10:15:37
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Posted by Martin Shaw 1 on 01/11/2018 21:23:22:

Hi Ron

That's pretty impressive, I'm not at all certain I would have undertaken that, but it has undoubtedly worked well. Some food for thought here.

Martin

Thanks guys.

Martin, if I managed it on your ex SX2 then with your new SX2.7 you should have no problem, it was a SX2.7 that Jason did a trial for me using the same ARC boring head that I used.

Bet your just a bit excited with your new machine on its way shortly.

Ron

Edited By Ron Laden on 02/11/2018 10:17:15

JasonB02/11/2018 12:38:03
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Posted by Neil Wyatt on 01/11/2018 20:48:59:
Posted by JasonB on 01/11/2018 12:19:47:

looks like it will just clear but not sure what the finish will be like as it is slightly negative rake

 

Isn't the rake angle of the vertical edge more important?

Yes as the cut is downwards not outwards but as the unground edges meet at something like 87degrees by the time the flat face has been tilted up to clear the bottom of the cut you are close to or into negative rake. I you take the longer yellow line to be the bottom of the cut, the tool will need rotating anticlockwise so the flat face of the carbide does not rub so then the shorter line will become vertical or past vertical and into negative top take.

dsc03305.jpg

Edited By JasonB on 02/11/2018 12:38:48

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