Thread: How do you centre bar for slotting in the mill (or shaper for that matter)

Originally Posted by pipeclay

Is your slotting cutter large enough to reach more than halfway down the side of your stock.If so use a piece of paper,bring the cutter in until it just starts to pull the paper out of your hand,then just keep moving the cutter until its in the centre of your stock,of course you would need to measure your cutter and stock to get centre,if that particular you can measure the paper and allow for that as well.

Do you have a angle plate that is higher than you stock when set up,if so place the angle plate against your stock and use either a set of inside calipers or verniers or telescopic gauges to set your cutter in the centre of your stock,if you don't have the angle plate you could use a heavy parallel or even an engineers square.

For getting close just use a rule in the above example.

For setting centre in the shaper you can use the paper between the side of the tool and the stock.

Thats the way I was shown and have always done. Pretty fool proof unless your chasing better than a thou or two

[QUOTE=Steamwhisperer;1653251]Hi Michael,
I use the paper method but the paper is a cigarette paper. Normally they are about 0.0015" thick so when the cutter grabs the paper you are within that distance from the side of the work.
This method has worked beautifully for a lot of years.
If the work is too large in diameter to get the cutter down the side then I do as Stuart said and use a Square with the paper. You just have to remember to add the thickness of the blade of the square to the distance you move the cutter over (or table under). This way backlash ceases to be a problem because you only travel in the one direction.

Phil[/QUOTE.My method too the trusty old fag paper method was a common set up since time immemorial,when most tradesmen smoked.With the non smoking policy now and unless you got your own rollie papers.1 pack last you a long time. Was shown to me that method from a crusty crafty old Scottish marine engineer.He served his time on the Clyde Glasgow at Brown Bros makers of fine ships Q E Q Mary etc.many fine stories of those hard and tough days.

If I can fit the thing in I use a Haimer Taster (What? You haven't got one Michael!). When I can't fit it in, which is more often the case, some half thou paper strip my old mate Bruce "Abratool" gave me, a loupe and a torch.

BT

Damn. It's sounding like I have to do things the mathematical way.
I was hoping that one of you guys had an old machinist's trick, typical involving a piece of brass wire, a lump of beeswax and a small oddly shaped piece of metal (cut by the light of a full moon and tempered in wombat spit).
Instead all I get is an old machinist's trick using rolly paper - admittedly getting as hard to find as wombat spit, but never the less...

Michael

I prefer the 2 paper trick, the second 1 is for the backie

Ok, enough of the rollies, beeswax and womabt spit...

On the mill, if really you needed it spot on, touch off the side with a led probe, then enter an offset in the dro by half the part width plus the probe offset, wind back till the dro reads zero...

If you weren't too fussed, just take a cut off the top and eyeball the center of the flat.

Regards
Ray

PS I can always pinch some papers off Josh if needed....

As luck would have it, I did find Keith Fenners method of locating centre to cut a keyway, and surprisingly it was in the series of vids, the first one of which I had linked to in my earlier post. If you have plenty of time, watch the whole series, but if you are time poor, watch from the 9 minute, 45 second point of this video which is the 5th in the series. He explains it much better than my explanation in my earlier post, and PDWs rather more succinct explanation later. Here is your chance to learn from a master. (Him not me, )
Rob.
Resurrection Part 4 - YouTube

Originally Posted by Ropetangler

As luck would have it, I did find Keith Fenners method of locating centre to cut a keyway, and surprisingly it was in the series of vids, the first one of which I had linked to in my earlier post. If you have plenty of time, watch the whole series, but if you are time poor, watch from the 9 minute, 45 second point of this video which is the 5th in the series. He explains it much better than my explanation in my earlier post, and PDWs rather more succinct explanation later. Here is your chance to learn from a master. (Him not me, )
Rob.
Resurrection Part 4 - YouTube

Cutting centred keyways is pretty simple. Cutting splines without a spline cutter is far worse as you need to do 3 cuts - one on each flank to get the vertical sides then a cleanup cut in the centre to remove the raised V left from the other 2 cuts.

So you have 3 separate opportunities to screw it up multiplied by the number of splines there are.

Note that I only would make splines this way for low power/speed uses though I have done it to make tractor PTO fittings when desperate.

PDW