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17th Nov 2020, 10:00 PM #1Senior Member
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Centering rectangular stock in 4 jaw
I am working on a project where I want to face off some rectangular stock and if possible drill a centre hole (although I could do that on mill later). I intended on facing one side, then flipping over to the other and have two nice parallel surfaces. I have centred round stock in the independent 4 jaw previously using a dial indicator but I am unsure of best approach with the rectangular stock. I wondered if I should pick a corner and basically find a sort of top dead centre to compare and adjust to? I am sure there is a better way so I hope someone can set me right.
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17th Nov 2020, 10:13 PM #2Gear expert in training
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I picked up this trick from an Abom video, it requires 2 centres, at least one of which should be dead. This works for clocking up any arbitrary point you want, not just the centre.
Make a punch mark in the centre of the stock, hold a dead centre between the punch mark and another centre which is in the tailstock, then indicate the "floating" dead centre. Picture...1000 words...etc:
PXL_20201117_111121068.jpg
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18th Nov 2020, 03:47 AM #3
Hi Ian, Guys,
That is basically the technique that I use ! Draw a pencil line from corner to corner and prick punch the centre. I have a 10 inch length of 5 mm silver steel rod with a point on one end which I clamp in the tailstock drill chuck, then using a dial indicator with an elephants foot resting on the rod. Adjust for no indicator movement as the chuck is rotated.Best Regards:
Baron J.
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18th Nov 2020, 07:14 AM #4Mechanical Butcher
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18th Nov 2020, 08:01 AM #5Philomath in training
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It should be no different to centring square stock, except do the opposite sides before moving around 90 degrees. I find that I usually have to wind the carriage back so I don't wipe out the indiator tip when I rotate the corner past the indicator. The centre in a punch mark technique will work, but relies on the punch mark being spot on. Using an indicator on the sides will get you closer to the true centre if it is important
Michael
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18th Nov 2020, 10:12 AM #6Diamond Member
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18th Nov 2020, 11:05 AM #7Golden Member
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I normally just draw 2 diagnose lines then eyeball it with the dead centre on the tailstock if accuracy is not required
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18th Nov 2020, 01:17 PM #8Senior Member
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I reckon I would be more concerned about how likely it will snap the tip of the tool off when you get out to the outside and there’s fresh air before the edge of the workpiece hits the tool. It wouldn’t matter if it was not exactly centred if you’re just facing it off would if?
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18th Nov 2020, 03:37 PM #9Golden Member
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I find it is better to use HSS for interrupted cut, the insert tends to chip/break.
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18th Nov 2020, 05:25 PM #10Most Valued Member
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18th Nov 2020, 07:56 PM #11
Spring Centre !
Hi Guys,
This is my spring centre, I usually use it for keeping taps straight when threading holes.
01-09-2018-001.jpg
Its home brew and very simple to make. Though not a good tool for centre finding !Best Regards:
Baron J.
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18th Nov 2020, 07:57 PM #12
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19th Nov 2020, 06:59 AM #13Senior Member
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19th Nov 2020, 03:51 PM #14Diamond Member
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19th Nov 2020, 04:32 PM #15Most Valued Member
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For a job like that, seeing as you mentioned using a mill, I’d use a face mill or fly cutter, then bore the centre hole. Only have to clean and oil one machine then...
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