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Member postings for John Pace

Here is a list of all the postings John Pace has made in our forums. Click on a thread name to jump to the thread.

Thread: Soba rotary table
14/03/2019 09:54:00


I just wonder how long rotary tables will be made in the conventional way .
Other threads on rotary tables have highlighted the strength problems
with worm and wheels .
This video shows these spiroid and helicron gears which can be made
with zero backlash.
https://www.youtube.com/watch?v=gRriAf5snqs

A photo here of a test gear hobbed using a 1 module cutter ,the worm would
fit in about the 1 o'clock position and have about 5 teeth in mesh at the same
time.
Johnspiral gear.jpg

Thread: Mixing Gear Module?
14/03/2019 08:38:32

Myford .8 module change wheel set and Warco Gh 1000 1 module change wheels ,both keep within the machine covers.

John.8 mod 127 changewheel.jpg1 mod 127 changewheels.jpg

Thread: MT4.5 sleeve
10/03/2019 10:28:06

Here is a drive unit that i made ,toothed belts work fine for these and don't leave a chatter pattern on the work and provide a positive drive.Three speed gearbox and variable speed motor gives a drive speed from 20 to about 700 rpm.

Johncylindrical grinding drive.jpg

Thread: Machining cork!
04/03/2019 20:07:13

Hi Maurice,

I you have ever used some silicone sealant the tapered nozzle that is on the tube always has some left over sealant inside that sets inside , pull it out and you have a tapered plug of silicone ,cut it as required to form a suitable silicone cork.

John

Thread: 4th Axis for Sieg KX1
04/03/2019 09:28:38

A 4th axis is an essential accessory and opens up what is possible to do.The compressor wheel on the left is milled from 2014 t6 aluminium 68 mm in diameter ,the one on the right is a bought cast wheel 66 mm dia for a KJ 66 model gas turbine.

John68mm compressor wheel.jpg

Edited By John Pace on 04/03/2019 09:38:33

Thread: Warco Rotary Table - What Grease?
25/02/2019 09:53:43

Double posting.

John

Edited By John Pace on 25/02/2019 09:55:36

25/02/2019 09:53:23

Rocol Tufgear universal open gear grease is a sticky grease that retains it's position when applied ,RS sell it part no 388 8465 may be cheaper elsewhere .Good for changewheels etc very messy.

John

Thread: Model gearwheel pump
22/02/2019 11:01:28

Some photos of a geared oil pump for a machine coolant
system.The gears are 1.25 module driven by a 12 volt
dc motor of about 20 watt ,pumps about 2.5 litre minute at zero
pressure through 2 filters to remove micron size particles
from the system.
The smaller gears are from various fuel delivery pumps for a
model gas turbine ,the middle size gears pump about 1 litre a
minute at about 40 psi,end leakage on the small gears is more
of a problem as they are only .050 inch wide and need
careful fitting.

Johnoil pump 2.jpgoil pump 1.jpgoil pump 3.jpg

Thread: Quorn Castings
12/02/2019 13:29:00
Posted by Emgeere"> 12/02/2019 10:04:39
John
 
Nice looking Quorn and a very well planned nest of swing out
drawers, is that your design ?
 
When grinding along the flutes of milling
cutters I thought the cutter should be ground
on the periphery of the wheel but above centre to
provide back clearance, how do you grind flute back clearance ?
 
Emgee
 
Just a matter of space saving ,some angle iron supports hold
the wooden trays on a single strut.
 
The photo shows in the foreground a post that is secured to the
table, this is a zero reference to the workhead axis,using a
dti the tip of the cutter is set to a zero position using
this reference.
Looking at the photo rotating the cutter anti-clockwise
increases the angle from zero to the desired amount .The
grinding wheel is at a shallow angle relative the the work
axis ,as can be seen by the black line around the edge the
point of contact is small as it should be.
 
Early on when i first made and used this machine this is
how i would set up,now i use the same basic method but grind
first the secondary clearance. The Quorn book seems to show
the primary clearance as 6 deg ,in a Dormer handbook this is
shown as " Clearance on body teeth , this varies progressively
across the range from 10 deg on smaller diameter tools to 5 deg
on the largest diameter . Secondary clearance ,this is 15
deg across the range".
 
Setting 15 deg on the machine ,20 motor steps = 1 deg ,rotating
the work shaft 300 motor steps sets the 15 deg.
When the cutter is ground, the secondary clearance can be
measured on the machine as in the photo diagram ,since from
this the true angle is known it is a simple matter to rotate
the cutter to set the primary clearance angle.
Page 94 of the Quorn book makes reference to grinding
on the periphery of the wheel.
 
John
Cutter clearance
 
12/02/2019 09:41:26
Posted by Derek hall 1 11/02/2019 13:01:12
 
 
I did my apprenticeship in 1974 to 1978 and in the stores in the
first year they had some ME magazines, and in one or two issues
was the description of the Quorn...one day I thought, I want to
make one of them! 45 years later I got the castings!..
 
 
I hope that you stick with it.The Quorn is an enjoyable thing to
build and when it is done you will have a very useful piece of workshop
equipment.
 
I built mine 30+ years ago and have added to it over time.

q5.jpg


The Quorn in it's basic form is unable to sharpen milling cutters
along the flutes with any great success along with many other
hobby type cutter grinders that use the same type of setup.

The problems are all the same the friction of the workhead and also
the guide rest in the flute of the cutter.
Even when attempting to do this there is a size limitation that
makes this impossible to do even if you were to have an air bearing
work holder.
In the first 20 years i had the Quorn i don't suppose that i tried to
sharpen along the flutes more than a dozen cutters, most of them
were not much better than before i started.


In the time since then i made this cnc grinder which uses the Quorn
head, up to now i have sharpened hundreds of cutters along the flutes
from 2,5 mm dia to 20 mm dia all of the cutters that i use, they
all come out as sharp as new cutters and in some cases sharper than
new cutters from some suppliers.
The resolution of the machine is 1/20 th of a degree and as such the
clearance angles can be set with this sort of accuracy.

John

cnc grinder1.jpg

Thread: The Diamond Tool Holder
01/02/2019 19:36:01

Posted by John McNamara 7/01/2019 13:23:07

Hi John Pace.

GMTA I made the same toolbit using the carbide shank from a
PCB drill, PCB drills are so tiny to hold up they are made from
very fine grain carbide. Tough too.

I milled a piece of key steel of the correct size and silver
soldered in place. Been using it for a couple of years. The ten
degree angle you normally use for the Diamond tool can be reduced
to around 5 deg by angling the template. More robust for heavier work.
However it will work fine as standard.

Regards
John

Hi John,

I don't use the supplied fixture to sharpen the toolbits,some while ago
I bought 10 off 1/4 square toolbits from J&l supplies they were on offer
at about 80p each 10% cobalt.
Both ends are sharpened as can be seen in the photo .I had this process
scribbled out on a piece of paper and have tidied if up here for use
on the Quorn grinder or tool grinders with similar axis. This may be useful
for others wishing to do this.The self centering 2 inch four jaw chuck is
from Chronos and makes this much easier to do.

Having 20 ground ends if one is dulled it goes in the grind box and
a fresh one fitted.

The carbide tips that are ground similar to a CCMT shape only need regrinding
on the top until the are worn down enough that the sides need doing again.
Grinding the carbide is best done towards the cutting edge to avoid chipping.
These days the tangental toolholder gets the most use.

John

Diamond toolholder toolbitsCarbide tip grindingHSS grinding

26/01/2019 10:25:11

I silver soldered this 1/8 inch carbide shank into a suitable size square piece,the edge is milled out about half the diameter and the piece soldered in ,it seems to work best if left as a round shank.The round piece fits neatly between the clamp.

The one on the left is ground to conform the the square shank ,because carbide chips easily when ground to the acute angles of the diamond tool a shallower angle is needed at the top and both the sides need a little grinding for clearance.

Useful for harder materials and maybe cast iron.

John

007.jpg

Thread: Occasional usage Sand blaster
16/01/2019 12:42:34

I built one of these sandblast cabinets 20 + years ago from
a kit of hardware parts and the drawings for the cabinet
made from plywood,it will run all day on the same size
of compressor.

It looks as if the vent on the back of the bin blaster has a
filter in it these are worse than useless as they block up very
quickly so the dust finds the next easy route out.I doubt
that it would be wise to use this inside the workshop you
would find out why the next time you use your lathe.

My own cabinet is sealed and vented externally.

Rubber gloves 24 inch in length are avalable from J&L
Pt no GLV-90082E.

John

005.jpg

Thread: Small Milling/Drilling Spindle (again)
15/01/2019 12:07:04

Posted by ega 14/01/2019 10:58:45

In the introduction to his 1997 book Harprit Sandhu invites corrections.
I wonder whether it would be possible for him to be invited to comment?

I bought the book partly because, having faced the challenge of building
the Quorn spindle I was interested in knowing if there were easier ways
to achieve the desired result.

Edited By ega on 14/01/2019 10:59:05


I too have built a Quorn spindle and with care they run well ,it must have done
as i have had it 30 years and it has never been apart.


The photo shows 3 grinding spindles under construction,based on the layout
of the Quorn type spindles with modifications.

The outer sleeve is bored through for a close fit for the bearings,in this way
the bearings will be in line axially.

The shaft is made with bearing seats this gets rid of the bearing spacer tube
and makes the shaft much stronger as it is larger in diameter in the central
portion.

The two sleeves seen in the photo, the shorter one is eventually loctited into
the outer sleeve in the correct position ,the longer sleeve forms the spring box
to push on the rear bearing much the same as the Quorn design.The spacing
of the bearing seats on the shaft is a few thousanth's more than the total
length of the two sleeves limiting the amount of axial movement.

The two screwed end caps similar to the Quorn ,the front one traps the
outer raceway ,the rear cap is clear of the bearing.
In this way a nut fixing is required at both ends of the shaft to trap
the inner raceways to the shaft, as these form part of the labyrinth
seals these are much easier to do.

Perhaps the biggest advantage of constructing in this way is that all
of the turnings are single operations and require no turnarounds for all
of the important features.
The bearings are SKF C3 Eco 17x 35 mm bearings rated for 25,000 rpm
and are more than good enough for the expected loads,i expect that
angular contact bearings a better bet if the spindles were to be used
for milling.

John

01  29.jpg

Thread: Holding work on the cross slide
22/12/2018 11:19:22

boring bar.jpgI had a similar problem with my Warco lathe .I made an add on plate the full length of the crosslide just over an inch thick ,it is held with six 6mm cap head bolts ,holes for mounting parts are drilled as needed.If your lathe is similar to mine about the rear third of the crosslide is little more than a cast in cover and is quite thin in section so careful placement of the bolts is required.

The topslide mounting ring will most likely be too far from the centre line of the machine to be of any use in holding work in any event to fit longer tee bolts you will probably have to remove the crosslide.

John

Thread: Gear cutting
01/11/2018 10:36:33

Hi Ian, The first photo shows the drive to the spindle ,as you can see the head is swung around by 180 deg and the drive gear is mounted to the main spindle.A reduction gear arrangement is clamped around the quill ,this originally was going to form part of the mechanism for a mechanical gear hobbing unit on the mill but was abandoned in favor of an electronic hobbing unit made by Richard Bartlett (Compucut).The keyed driveshaft transmits to the spindle via the bevel gears .The hardened spindle runs in bronze bushes in the spindle housing,the cutter is home made as in the book Gears an gear cutting by Ivan Law and at 1 1/2 inch diameter protrudes just enough below the edge of the spindle block to clear.The spindle block as can be seen in the earlier photo is held on the rear of the head column ,a diagonal brace connects to the main column and provides considerable support  to  the mounting.

The second photo shows a close up view of a shorter 20 DP rack.The vice provides the main support ,the two blocks either side are secured to the table with T nuts and milled level in situ to provide the support either side of the vice jaws.

 

milled rack 2.jpg20 dp rack.jpg

Edited By John Pace on 01/11/2018 10:55:47

31/10/2018 19:25:42

Here is a 20 dp rack cut on my Warco mill ,as is usual with these sort of jobs there is some parts that need to be made to enable this to be done .As the machine is part cnc the spacing and driving the cutter through is done with a small cut file ,the cutter depth is set on the knee.The rack has about 160 teeth and is about 25 inches long.

milled rack 1.jpg

Thread: 3 in 1 sheetmetal bender
17/09/2018 12:38:33

I have had this Warco 24 inch formit machine for nearly
20 years,clearly these 3 in 1 machines will never compete
with the more industrial size sheet metal work machines.
Mounting the unit on the frame seen in the first photo
has made the the unit much more rigid and capable of cutting
and folding beyond the stated capacity ,mounted on 4 castors
allows it to be stored under the bench alongside the 4 1/2 inch
cut off bandsaw also reduced in height.
The frame is welded up from 4inch x 3 inch angle iron,a welded
box is formed which sits under the lower blade of the shear.
In the second photo you will see a jack screw that supports
the cross plate and also two welded on blocks and two screws
that provide some rearward thrust on the lower blade,the two side
pieces are a convenient mounting for the castors ,a single
piece of angle at the rear third photo completes the frame a
small metal tray not shown rests in the frame to catch the cut
off parts.
Brushing on some cutting compound on the guillotine ,i use
trefolex makes cutting a little easier especially with stainless,
also greasing the vee and blades can also make the folding
easier.

Like all of these Chinese products the fixing screws and bolts
are not the best quality,one of these end bolts at the lower end
of the curved arms bent and broke off the end of the arm last
photo ,i can't complain too much about this as i was folding
some 2mm steel sheet,the holes in the ends of the guillotine
plate are drilled much deeper than they are tapped and is worth
tapping them out to full depth and replacing the bolts with
a better quality.
All in all a very useful piece of equipment if you can live with
the usual Chinese construction.

John

formit 1.jpgformit 2.jpgformit 3.jpgformit 4.jpg

Thread: Please help identify these tools
07/09/2018 11:34:57

Hi Wayne

The first photo is the auto feed bracket from a Dore boring head ,the photo here shows the auto feed in operation ,hope you managed to get the boring head as well a useful piece of tooling to have.

Johndore boring head auto feed.jpg

Thread: Gear Hobber : Design ideas please ...
30/08/2018 13:54:28

Hi Michael

Have sent you a PM

John

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