Hemingway quick set Keats

[Roger B]

I picked up my Keats kit when I was in England and made a start today. This is my first attempt at making something from castings 

As usual it is on the limit for my machines. By filling out the slots to fit the jaws on my 4 jaw chuck I could just clamp it. The books all say you should start with a deep cut on castings to get through the skin. I didn't think that this was rigid enough so used a carbide tipped tool and some hope  It seemed to work. In the end the faces were flat and parallel along the length, but tapered about 0.04mm across the width. I would like to improve this, but suspect I should wait and see if the casting relaxes a bit after it has been machined. Is this likely?

Milling the first slot went ok. I am using a 10mm cutter at 560rpm and increased the depth in 1mm steps. Does this sound reasonable?

I will hopefully finish the base tomorrow and start working out how to hold the V block.

[Roger B]

A few more steps. Holding the V block for the first cut was quite difficult as nothing was very flat or parallel. Once one face was reasonable I could get a good fixture. The first results were not as parallel as expected (~0.1mm in 70mm error  ). On further checking it appears that the top of the cross slide is not parallel with the bed (~0.1 mm in 60mm error) and I must have put the block in the 'wrong way' round. As I now know the problem I can clock the components against the bed and compensate  I think 

[Roger B]

By cleaning and adjusting the gib I reduced the error to ~0.05mm in 60mm, but the residual error seems to be in the thickness of the crossslide. I will have to see if I can correct this 

[Jo]

Roger, Yet again you choose to make something massive on what I considered a small lathe. Most impressive 

Jo

[fumopuc]

Hi Roger, I am following with massive interest. This kit is also on my wish list.

[steamer]

As to your lathe alignment.    That surface isn't as important as the flay ways on the dovetail.     Additionally the surface of the mill table should be parallel to the lathe ways.   

You could shim the part to account for the tilt.

Dave

[Roger B]

Thank you for the comments. I already have a 'normal' Keats (as from RDG, RC etc.) but it is just too big for this lathe. It was very useful on my 90mm center height Chinese machine.

In looking for something smaller I found this from Hemingway. The two castings also appear to be available from College Engineering Supplies.

http://www.collegeengineering.co.uk/KeatsAngles.htm

The drawings and instructions need careful study as there have been some problems where it has been converted to metric fasteners, for example a 3/16" slot for an M5 thread.

I need to study the lathe cross slide more closely. A quick check last night suggests that the flat surfaces on the carriage are true to the bed, the milling table I bolt to the cross slide is also flat and parallel (checked with a 0.01mm DTI not my new 1 micron one  ) so the problem appears to be in the cross slide itself. As a first shot I will take it apart and check it on the surface plate.

[Arbalest]

Nice job.  Looking forward to seeing how you approach the Vee cutting.

[Roger B]

I checked the cross slide last night and it also appears flat and parallel to ~0.02mm. When I put it all back together the variation is around 0.05mm across the width of the cross slide but I don't see where it is coming from   

I have been think about how to mill the V. One option is to use the tilting head on the mill, the other is a set up with V blocks. I am tending towards the V blocks at present, but I will need to add some stops to avoid the V blocks moving. Needs more thought   

[sco]

I may be wrong but that looks like the load line is outside the Vee of the Vee block so I don't think will work.

I would be thinking about machining the Vee first and then squaring the other surfaces up to it.

Simon.

[steamer]

Drill a pair of holes parallel to the "V" and put pins in that are pressed into the milling straps.   That way you can grip is far lower!    That set up looks scary to me!

Dave

[Arbalest]

I milled a quick V jig for woodworking tool sharpening. I set the block up on the mill at work and cut the V with a 3/4" cutter. I didn't measure the angle when it was finished but it sure wasn't 90°, more like 92° maybe more. It didn't matter for my purpose, it was only to support spindle gouges for sharpening. I would though like to see the right way of getting a perfect 90° V. 

[Roger B]

Drill a pair of holes parallel to the "V" and put pins in that are pressed into the milling straps.   That way you can grip is far lower!    That set up looks scary to me!

Dave

There need to be two M5 clearance holes in one end. I could put them in both ends and clamp as you suggest. That's the advantage of the forum you post a problem and get ideas back 

[steamer]

Drill a pair of holes parallel to the "V" and put pins in that are pressed into the milling straps.   That way you can grip is far lower!    That set up looks scary to me!

Dave

There need to be two M5 clearance holes in one end. I could put them in both ends and clamp as you suggest. That's the advantage of the forum you post a problem and get ideas back 

There ya go!....

Dave

[Roger B]

I squared up the other two faces. They had the steepest lead so I could not get through the skin in one cut, but it didn't seem to cause problems.

I decided that the best way to cut the V would be only the use the end of the end mill, turning the block round to cut each face. This would leave a small ridge at the bottom which would be cut away with the final slot. I clocked a solid fence on the table to keep the V blocks aligned and turned the block round for each cut, keeping the depth the same. That all seemed to work well and the V is 90° as far as I can tell with my square.

When I changed the speed for the final 2mm slot I found I had left the mill at 1100 rpm from cutting the slots in the base  I may have got a better finish at 560 rpm 

Next step cut the locating slot and then clean up ready to cut the steel components.