Milling on a Lathe with a Vertical Slide

So bit more progress today.

Marked the location needed for the recess and drill a shallow hole:

Once in place the Alen Head screws protrude through the Cross Slide.

So I needed to shorten the allen head screws to about 18mm total length.

Then. once the base plate was fitted and line up, I marked the position of the third bolt and drilled and recessed the base plate.

With the base plate back in place, I used a 5mm drill to transfer the hole through to the cross slide and then tapped it. The Alen screws are 5mm so I looked up the drilling size for a 5mm thread using an M5 x 0.8 Tap and it was 4.2mm. I only had a 4mm drill so that would have to do.

Once drilled I carefully tapped it (not to self get some 'vee' blocks to help straight drilling and tapping.

And here it is bolted in place.

Next job was to mark and drill for the 8mm studs, I marked and centre punched them but time was tight and my dinner was calling - Bratwurst.

Sorry forgot to add the pic:

So now I have marked the positions for the studs, I need to seek some advice.

The plate is 10mm, which is the same thickness used by Steve where he covers making a baseplate like this. In his video he does not go into drilling and tapping the holes for the studs or bolts (he used bolts on the RH side).

I bought some 8mm threaded bar so I'll use studs for now but may change some for allen bolts later?

As he does not show the detail, I don't know whether to drill all the way through the base plate and tap the entire depth of the hole or whether to use a blind hole and tap to the bottom? What I don't want is the studs to wander too far otherwise the ones on the LH side could fowl on the Cross Slide Threaded Bar.

I only have a very small cheap Tap and Die set M4 - M8 with only one tapered for each size so I'd need to by a plug Tap. I have just ordered a 3 piece 8mm x 1.25 Tap Set from RDG which comes with a 6.8mm drill bit.

Question: If I do blind holes for the studs, what depth into the 10mm plate would you recommend?

Edited By JasonB on 07/08/2021 16:52:34

8 to 10mm, and I'd go all the way through.

Though you can convert a taper tap to a plug tap by grinding the taper off, it's easier and stronger to tap clear through a hole, than it is to blind tap it. Apart from anything else, through tapping much reduces the chance of breaking the tap.

If the bolt isn't allowed to go through the hole, ding the last turn of the thread with a centre-punch to jamb it.

Rule of thumb, threaded holes should be the same depth as the diameter of the bolt in steel, 1½ x deep for soft materials, and twice as deep for mixed metals, like a steel bolt into aluminium plate. So 10mm is good for up a 10mm diameter bolt, and comfy for an 8mm bolt.

Studding isn't strong as steel goes. Studding threads are a loose fit in ordinary mild-steel. Loose threads are easier to fit, but weaker. Cheap and handy rather than aerospace! Studding is perhaps a quarter of the strength of an Allen Bolt of the same diameter because Allen Bolts are are made from stronger steels and with tighter threads.

For this purpose, the extra strength of an Allan Bolt isn't required, because mild-steel is good for 10 to 20 tons per square inch, but never a good idea to replace existing Allan Bolts with studding or home-made nuts. In William's case, his 10mm mild-steel plate would fail before an 8mm Allan Bolt, but not likely to happen unless the lathe has a serious accident!

Dave

OK sounds good. I'll tap through and centre punch the bottom threads.

Based on the depth v diameter rule I shouldn't use and allan bolt then from underneath, because recessing the head of the bolt would mean there was no meat for a thread?

As S O D says, always work on the basis of a minimum of 1D of thread engagement.

Yes, tap through and then centre punch the bottom threads, so that they cannot protrude through the T nut, and are unlikely to unscrew when the nut is slackened.

Howard

So I ordered a set of 8mm taps. Which one is which? As in Taper, Second and Plug?

Right to left taper, second and plug. You can see the taper tap has more "flat" crests due to it's longer taper

Ah thanks, I thought as much but wasn't sure. I was thinking the plug would have no taper, but I guess it has to, to be able to start cutting?

In many cases, especially in 'easy' metals like most brasses, allis and mild steels - and if you can chamfer the hole entry - the plug will be enough on its own. It's when you want a high-precision thread in more serious steel that you need the full series.

A little time to progress with this project today. Started by drilling out all the stud holes ready for Tapping, I started with a 4mm then a 6mm and then finally the 6.8mm that came with the 8mm Tap Set.

Then I tapped the first hole and checked the threaded bar.

Next I tapped the remaining 4 holes and marked out 5 pieces of threaded bar, each 50mm long.

I then put the angle plate in place and fitted the 5 studs, washers and nuts.

Sorry no pic of them all in place but you get the idea.

Once it was clamped in placed it was very rigid, however when grabbing and rocking the angle plate it showed a little movement in the cross slide?

Eager to test it out I grabbed the only flat metal I had, some scrap square bar brass. I clamped it in place using a Soba Stepped Clamp Kit. Doing this highlighted the need for a better solution, anyway I cracked on.

The shot above was taken after I had successfully taken a small cut out of the lower centre of the bar with an 8mm End Mill.

So my first ever modification and my first ever milling operation

This was done in two passes, and you'll see where I went a little deeper in the middle.

So what next?

Well, whilst the current setup would suffice for the one particular job I have planned, however improvements are needed.

1. I need to make some thicker bushes to replace the washers I have used on the 8mm studs.

2. I need a vice held in place on the Angle Plate with T Nuts.

3. And for a complete solution I need to invest in a Vertical Milling Slide to give a range of movement and the ability to move the workpiece into position for machining.

Edited By William Harvey 1 on 02/09/2021 18:10:21

So in order to upgrade and improve, can anyone recommend some form of vertical slide and vice that I could bolt onto the angle plate?

I could invest in a vertical milling slide such as the first two listed here, but I would need to make another adaptor plate (which I can do)?

I’m having trouble finding a suitable vice for this setup.

As sent in this thread, I have an angle plate, and I have also just taken receipt of a Myford style double swivel vertical milling slide.

I have been suggested the Warco 50 or 60mm jaw width small vices as the bolt through the vice base, but they are out of stock.

The one in the pic looks similar to a Chronos one that has fixings on the side but not sure if it will fit?

Bill,

That vice in the pic will fit. The two bolt heads you see hold the vice on via t-nuts in the v. Slide slots. You also have a choice of slots which improves versatility.

David.

You look to be set up and ready to go!

OK, it will not be as versatile as a milling machine, but not everyone needs to mill a 12" long keyway!

If you treat the set up with respect, and don't ask too much of it, you have a whole new range of options open to you!

Enjoy!

Howard

David, do you mean the Chronos one that I linked will fit?

Yes, as shown in Jasons post above.

David.

No not the one in the pic the one I linked from Chronos, although it does look identical?

it’s a Soba Vice

**LINK**

The SOBA vice in your link is the same as in Jasons pic. If you search Chronos for small milling vice for Myford you will get a choice of 4 pi x. On of them clearly shows the mounting holes in addition to the 4 edge notches. The only variant in Jasons pic is some nuts replacing the knurled end of the operating screw.

Awesome, thanks for the clarification, I’ll get one ordered up. 😂