Drill the smaller size hole right through both parts with an ordinary drill. For your size there is no real need for the extra expense of a taper drill.

and go careful with the taper reamer, it is very easy to make the hole too large

I've not seen a tapered drill bit for steel. Drill bits cut on the tip of the drill, not the sides and reamers cut on the sides.

I have see a combination tapered drill / reamer that cuts on both the end and on the sides but only for use in wood.

Where do you get taperred drills for steel ?

Paul.

Taper reamers were made with straight flutes and spiral flutes, it was accepted practice that the sraight flutes were for hand reaming and the spiral for machine reaming,I have aquired an assortment of taper reamers as they were used on the better class stationary engines .Taper pins if fitted correctly are far superior to roll pins,though a lot more expensive to drill and fit.I have always just used standard drills , at work it was the same,though no doubt I expect manufactures who used them frequenly would have some sort of taper drill to rough them out prior to reaming, when taper reaming on the smaller sizes I would recomend reaming by hand ,using an Eclipse "T" type tap wrench,as the large end of the hole has a relative lot of material to remove ,remove the taper reamer frequenly as the flutes fill up with swarf which will jam the reamer and break it,I have seen a couple of reamers shattered in my dim and distant past. in those days the lubricants were either oil from the can or soluble oil, modern lubricant like Rocol does make it easier. when fitting the pin try to leave a small portion of the pin visible at each end so that in future you can see from which end the pin has to be hit to remove it ,of couse if the the shaft and collar or cam etc rotates at high speed then the pin may have to be flush to avoid catching into anything though when stationary engines and lots of mechanical equipment were made around a hundred years ago ,there lots of bits of rotating and unguarded shafts visible.Another point when removing taper pins, always try to hit the pin dead centre and do it with a single heavy blow, lots of lighter blows just burrs the pin over,and make sure you are hitting the small end ,and do not use long parallel pin punches,they are to springy use a punch which is tapered from the body down to the business end .start the pin moving and then knock it fully out with a parallel pin. If you have to drill an old pin out which has been peened over or rusted in ,then try to make sure that the pin is vertical,I have found lots of pins where the pin has been drilled,the drill gone off centre and at the small end of the hole ends up as a figure of 8 shape. And finally the when driving out a pin make sure the shaft or collar is well supported on a solid block of iron.

Unless the angle of taper is different,

It is. 1:48 for Imperial and 1:50 for Metric.

We used the taper drills before reaming when installing taper pins at my last employment – as well as having the overall taper they also have notches in the flute edges to break up the chips. They required regular removal from the hole to clear the build-up of chips.

Nigel B.

I wondered what the difference was between metric and imperial.

4% difference in taper. 1:48 for imperial and 1:50 for metric.

Do you finish the pin flush or raised and rounded, or is that personal preference?

Mine was a permanent fixture, so not only made flush but staked as well (shrink fitted, fitted pins, loctited and staked🙂 ). It will never come apart, hopefully. I do like the ‘belt and braces’ approach if possible.🙂

HI Chris,

You have some good advice here, not a lot I can add.

I bought my taper reamers from Tracy tools, good company, never bought anything from them that I have been unhappy with.

I made some twenty tooth drummond gears many years ago. Drilled the pin holes the same size as smallest diameter and then reamed by hand for the pin. Very easy in cast iron.

From your first post in this thread you say you "admire" the taper pin method of securing the topslide handle on your M type. WHY?

Do you plan to remove the pin for any reason. If you are, good luck, they can be right b******* to get out. If and when the handle is off the machine do fit a topsllde index dial before replacing it, not difficult to make one, more details on request.

Geoff

Sometimes handles were screwed onto the end of a Leadscrew, so that backlash between the handle and the slide could be taken up by adjusting the position of the handle. If memory serves correctly after so many years, this was the case on the ML7 Cross Slide.

Howard

Hi Vic,

Looks like it to me! So pinning the handle seems to be the way to go

The nuts will minimise end float of the Leadscrew relative to the Cross or Top Slide body, but can't do anything about backlash between the Leadscrew and the main nut.

Howard