Simple file guide - a version for quick change tool posts

[romartin]

[SIZE=+2]SIMPLE FILE GUIDE - A VERSION FOR QUICK CHANGE TOOL POSTS[/SIZE]

Since I now have a QCTP and greatly appreciate its convenience, I get unreasonably annoyed when I have to take it off to remount my old monotool holder because I need to use an old tool for which I haven't yet made a QCTP holder. In particular I had to do this to use the Simple File Guide (see [thread]18274[/thread]) in order to make the hex section of some special nuts. So I decided that the following day I would make a holder for the File Guide.

As often happens the night brought council. Rather than simply make a holder for the existing File Guide it would be better redesign the guide so that the distance between the file and the lathe axis was adjusted by the QCTP's ability to move a holder up and down the dovetail. The result can be seen in the photo below, where the new QCTP version of the Simple File Guide is seen helping to make it's own lock nut.

Unlike the original design, the file is always horizontal. This has the advantage that the File Guide can be removed from the tool post without losing the setting of the distance of the file from the lathe axis.
As in normal QCTP holders, this height is regulated by adjusting the height wheel and associated locknut. However with respect to normal tool holders this File Guide has a much more robust height screw (diameter 8mm instead of 5mm) and the wheel has graduation marks around its rim to help with adjusting the height of the file. The thread on the height screw has a 1mm pitch so one turn of the height wheel moves the file by 1mm. The resolution of the graduation marks is 0.02mm.

Note that the height reading from the wheel is not absolute - the graduations are used to move the file up or down by a precise amount.


For example suppose we want to make a hex section with 13mm across the flats.

1. Turn the part to have a diameter of 1.1547 x 13 = 15.01mm (diameter across the vertices).
2. Set up your indexing method (gear train or whatever) so that you can position the part correctly for each of the six faces.
3. Mount the File Guide on the QCTP and set its height so that the file just touches the part.
4. Use the height wheel graduations to drop the file by half of the difference (in this case almost exactly 1 mm)
5. Position and then file each of the six faces.

 

[bhowden]

Small world. I made one last night as well. Yours is much prettier! Not having a mill I welded a piece of 1/2" mild steel onto a piece of 1/4" plate and set it in an existing holder. One thing I have not seen before that worked very well was I used a stack of 4 skate bearings for each roller. The hardened bearings seem to stand up to the file fairly well and they are sealed to keep swarf out. An advantage of using an existing holder that I had not anticipated was that I was able to file the piece that chucks in the holder slightly off square to get the rollers to run perfectly parallel to the lathe axis. I drilled the holes with a drill bit chucked in the lathe headstock but I tapped the holes by hand and must have got them slghtly off square. Time for a tap fixture for the lathe.....

Brian

 

[romartin]

Hi Brian.

Yes its a small world (and shrinking fast) thanks also to Internet and it's forums! I dont have a mill either; I dream of getting one but, apart from funding, I dont really have the space in my workshop to live with it. The six faces of the rectangular holder (110x29x22) were faced off with the holder in the four jaw chuck, and then the rest of the machining was done with my lathe in its milling configuration.

I will remember your idea of using skate bearings.

 

[gus]

Hi Ian,

Your QCTP looks great. I am about to complete mine this week. Admiring your tool height adjusting knob with graduations and the cam lock. The Hex Head file jig is a superb idea.
My W.I.P. QCTP is shown sitting on a poor man's marking plate which a recycled valve plate.

 

[romartin]

Hello Gus,

Thank you for your kind words. My File Guide gets a surprising amount of use, not only for making hex or square sections but also for making rounded corners as I tried to show in the thread refered to above.

Your QCTP is coming on very well!. I have some questions about it if you dont mind. What material did you use to make the tool post itself? I cant tell for sure from the pic. What kind of locking mechanism will it have? Do you make the tool holders and if so, from what material? Do you have a mill or do you make do with milling on your lathe like I do?

I now have quite a few tools permanently assigned to apprpriate holders and am presently making a holder for my dial guage. However I've been putting off making the holders for round HSS bars for boring tools because I'm unsure of the best way to fix a round bar in a tool holder. The design I've got, copied from a design published by Nifty, makes a hole right through the length of the holder (71 mm in my case) and then makes a slit from the edge of the holder into the hole also down the entire length so that the bar can be squeezed by three or four bolts. Nifty shows this sort of design for both 10mm and 12mm bars but I use 5mm and 8mm bar and I'm not convinced firstly that I can make such small holes straight enough and secondly that I can squeeze the bars enough to keep them in place when boring.

Do you have any suggestions?

 

[gus]

Drawing came from UK Model Engineer's Workshop Magazine December 2013 issue no.197.
Material uses was Bright Mild Steel bar. Cam lock system.

As for the adapter ,you could use use decimal point drills with ample tapping oil to get good finishing.
The slit could be done with slit saw. I may try making one as I was give an Eclipse boring cutter.

Bye now and about to go to balcony machineshop to finish up the cam.Cam pistons done with "O" as spring.

 

[romartin]

Thanks Gus.

 

[gus]

Thanks Gus.

Completed QCTP at last.Will do fine tuning as I use same.
Here is a shot.Passed by a "Nuts & Bolts" Hardware Shop.Could not resist buying the Red Plastic Knobs.
For this round using a 20mm DoveTail Cutter made it easier as I could take heavier cuts and with the use of Tapmatic Fluid,the cuts were easier and finishing as good.I wrecked all two pcs 3/8 Dovetail Cutters.Good lesson.Will avoid using such small cutters.
Sharing my QCTP foto with Ian.


Merry Christmas!!!


Gus







Merry Christmas!!!


Gus

 

[romartin]

Bravo! And a Merry Christmas to you and yours!