Boring in the lathe

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Boring in the lathe

This topic has 13 replies, 5 voices, and was last updated 7 January 2018 at 16:04 by Tim Stevens.

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6 January 2018 at 18:20 #335625
Tim Stevens
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@timstevens64731
When boring using a conventional boring head in the tailstock, I usually position the adjuster dial upwards (for visibility and access), and the tool edge downwards. This seems to work OK. But is there any advantage in using the tool upwards in this set-up, or setting the boring bar with the adjuster horizontal, and the cutter towards, or away from, the adjuster dial?

It seems to me that the sideways option can result in the forces on the tailstock moving it sideways where there is (inevitably) slack in the guides, whereas the up-&-down forces are better held firm by the tightening of the tailstock.

But are the other factors at work?

Regards, Tim
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6 January 2018 at 18:20 #9036
Tim Stevens
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@timstevens64731
tailstock boring head – tool position?
6 January 2018 at 18:29 #335628
JasonB
Moderator
@jasonb
Can't say I have ever used the boring head in the tailstock for boring holes. I just use a boring bar in the toolpost which is more rigid and you have power feed for a better finish.
6 January 2018 at 19:21 #335636
Oldiron
Participant
@oldiron
I must agree with you JasonB. Its much easier to just dial in (or is that out) a couple more thou on the cross slide than messing with a couple of Allen keys to adjust a tail stock boring attachment.

regards
6 January 2018 at 19:46 #335642
Joseph Noci 1
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@josephnoci1
I think you misunderstand Oldiron…Using a boring HEAD in the tailstock is very convenient. You adjust the cut by means of the micrometer adjustment on the head itself – no need to mess with Allen keys.

Tim, I use that method often, especially when boring a number of inners to the same size – rough with boring bar close to size, and then finish with the tailstock/boring head – However, not when better than 0.01mm fit is required!

Also, I set the cutter so that it is horizontal, same as would be with a boring bar in the toolpost. I find that the accuracy is better that way – tailstock is pulled down, which seems less movement on my lathe that sideways. However, good accuracy is hard to achieve as there will always be play in the barrel to body fit.

Joe
6 January 2018 at 20:15 #335643
JasonB
Moderator
@jasonb
Posted by Joseph Noci 1 on 06/01/2018 19:46:28:

I think you misunderstand Oldiron…Using a boring HEAD in the tailstock is very convenient. You adjust the cut by means of the micrometer adjustment on the head itself – no need to mess with Allen keys.

Joseph, many boring heads have the micrometer screw turned by means of an allen key and the head is also locked and unlocked with an allen key to make these adjustments
6 January 2018 at 20:32 #335645
Oldiron
Participant
@oldiron
Joseph Noci 1 Both my metric and Imperial boring heads are adjusted using 2 Allen keys. one to adjust and the other to lock. Both have 2 different size keys.

regards
7 January 2018 at 10:52 #335674
Joseph Noci 1
Participant
@josephnoci1
Ah, Well…..

Joe..
7 January 2018 at 11:55 #335682
nigel jones 5
Participant
@nigeljones5
I recently tried the boring head in tailstock method and found it highly unstable compared to using a normal boring bar in the toolpost – wont try it again.
7 January 2018 at 12:17 #335688
Tim Stevens
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@timstevens64731
My question was not asking about the wonderful advantages of other methods, but your experiences of this particular method in various positions.

In case it helps, I have currently no suitable boring bar for the size of hole involved, so it's tailstock (with all its faults, no doubt) or nothing. I've tried nothing and it does not work for me. I won't try it again.

cheers, Tim
7 January 2018 at 13:14 #335695
JasonB
Moderator
@jasonb
Tim, if the cutter in your boring head fits the hole why can't that be held in the toolpost?
7 January 2018 at 15:35 #335715
Tim Stevens
Participant
@timstevens64731
JasonB, the answer is simple. My boring head, bought for my Myford, is inch, so the cutter is half-inch diameter, and I've pushed as hard as I can, but it won't go into my metric tool holder which is 12mm. I did think about making a half-inch adaptor, but that needs me to bore a hole which is smaller than my boring bar will fit. Deja vu, anyone?

The sooner we get out of the EU and our metric tooling is all replaced by the government at EU expense with proper English sizes, the better. That was what the people voted for, after all.

Cheers, Tim
7 January 2018 at 15:54 #335721
JasonB
Moderator
@jasonb
You don't want to worry if the bar won't fit the toolpost, have you got any G cramps? That 12mm slot in the tool post will make a very good Vee block and fits all international standards
7 January 2018 at 16:04 #335724
Tim Stevens
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@timstevens64731
JasonB – the tool holder I have is designed for a boring bar, and has a 12mm hole through it. So, while I agree that I could remove the QCTP support and replace it with my old 4-square tool holder (like yours), and then use engineers clamps to hold the bar against the corners of the slot, I would still face the problem of height, and I was keen to get the job done before it went completely dark.

Tim
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