Model Engineers' Workshop - August 2022

70 Pages·2022·23 MB·English

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3 A CHAINSAW CHAIN ALTERATION TOOL
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Another practical build from Will Doggett’s workshop
THE MAGAZINE FOR HOBBY ENGINEERS, MAKERS AND MODELLERS AUGUST 2022 ISSUE 318 WWW.MODEL-ENGINEER.CO.UK
THE SHOWS ARE BACK!
2022 will see the welcome return
of model engineering exhibitions!
STAN BRAY
COMPETITION £5.75
1925 -2022
We pay tribute Win an English Wheel for
to our founding working sheet metal in our
Editor FREE competition!
INSIDE THIS ISSUE
GOING BACKWARDS - BRIAN WOOD DEFIES CONVENTION TO CONVERT A CNC MILL TO MANUAL
MY LOCKDOWN PROJECT: HOW LAURIE LEONARD KEPT HIMSELF BUSY IN 2020
AN INSERTED SHELL MILL FROM HOWARD LEWIS HINTS AND TIPS ON USING SPRINGS
MAKE AN OPTICAL PUNCH – ONE OF STAN BRAY’S CLASSIC BUILDS
BEGINNERS’ GUIDE TO JOINING TECHNIQUES BETTER BEVEL GEARS.

On the
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August 2022 3
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Essential reading before
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Contents
9 Converting a CNC to manual
4499
Brian Wood describes the process of
converting a CNC milling machine to
manual operation.
15 Beginners’ Workshop
Following on from last month’s overview
of different spring types, Geometer
discusses testing and fitting springs.
18 Stan Bray 1925 - 2022
We pay tribute to Model Engineers’
Workshops originator and first editor.
19 Home Made Precision Optics
In celebration of Stan Bray’s inimitable
style, we bring you this article by him
from the very first issue of MEW in
1990.
26 Win an English Wheel
Enter our free competition to win this
useful tool for working with sheet metal.
38 An Improvised Steady 56 Bob’s Better Bevels
27 A Thrust Measurement Rig Geoff Theasby uses a wooden jig to In part 3, Bob Reeve looks at bevel offset
Keith Beaumont explain how to make simplify a tricky operation. calculations.
a thrust rig for testing different model
internal combustion engines. 40 Building a Free Pendulum Clock 62 Regrinding a Shell End Mill
Tony Jeffree has further information Howard Lewis on grinding cutting
32 Joining Metals on his electronically controlled free inserts and making a jig for resetting
Stub Mandrel reviews the three main pendulum clock. them in their holder.
ways of joining metals.
46 A Ride on Walker
34 A product of Lockdown Stan Nesbitt made a custom walker
Laurie Leonard tells how he kept himself to help his wife develop lower limb
busy during the long days of lockdown. strength.
49 A Chain Alteration Tool
Will Doggett makes another well-
presented tool, this one is for spin
riveting chainsaw chains.
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Regulars
THIS MONTH’S BONUS CONTENT
3 On the Editor’s Bench Log on to the website for extra content
More news about changes to the magazine.
16 Scribe A Line Visit our website to access extra downloads, tutorials,
More feedback from readers in the UK and around the world. examples and links.
Send your own thoughts to [email protected]. www.model-engineer.co.uk/extracontent
31 Readers’ Tips Other hot topics on the forum include:
This month’s winner is an idea for mill gib locking. What does your casting setup look like, and results?
Comparisons of casting setup and results, by Luker.
48 On the Wire
Details of our photographic competition. My Casting Blunders and Successes
More on casting, by Pat J.
66 Readers’ Classifieds
A packed page of readers’ sale and wanted ads this month. Dividing head attachment
Installing and using a dividing head of a Myford Super7, by
Eliza Bruml.
Phosphoric Acid experiment
Derusting experiment, by Chuck Taper.
Come and have a Chat!
ON THE COVER ››› As well as plenty of engineering and hobby related
discussion, we are happy for forum members to use it
The cover of this issue shows a to share advice and support. If you feel isolated by the
Des Clark with a shaper at the lockdown do join us and be assured of a warm welcome.
2015 Bristol Model Engineering
Show. This month we got
confirmation that the Midlands
Model Engineering Exhibition will
be going ahead in 2022. CLASSIFIEDS EXTRA SUBSCRIBE ARCHIVE SUPPLIERS
August 2022 7
SMOOTH, QUIET, HIGH PERFORMANCE VARIABLE SPEED
CONTROL FOR LATHES AND MILLING MACHINES
Managing director George Newton, originally from the British Steel industry where he worked with 20,000 HP rolling mill drives is also a
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For the Myford ML7, George and his team produce the AV400, a complete ‘Plug & go’ solution including a new variable speed motor that
meets the original Myford motor specification, has the correct 5/8ths shaft diameter and is a direct fit
The ‘AV’ range is extended with the AV550 & AV750 for the Super 7 lathe giving a choice of 3/4HP & 1HP motor power
Full Torque is available from motor speed 90 - 1,750 RPM. Advanced Vector control for maximum machining performance. Prewired and
programmed ready to go. The AV400/550/750 speed controllers have an impressive 10 year warranty for the inverter and 3 years for the motor
(Terms and conditions apply). Over 5,000 units supplied to Myford owners. Speed control solutions also available for other lathes including
Boxford, Southbend, Colchester, Raglan etc call or email for details. Technical support available by telephone and email 7 days a week.
Newton Tesla (Electric Drives) Ltd.
Warrington Business Park, Long Lane, Warrington, Cheshire WA2 8TX,
Tel: [phone] Email: [email protected]
Visit https://www.newton-tesla.com for more information.
Follow us on Facebook: www.facebook.com/NewtonTeslaLtd
Si (Systèm international d’unités) Newton, unit of mechanical force, Tesla, unit of magnetic field strength
CNC to Manual
Converting a CNC
to Manual
Brian Wood explains how and why he went about fitting manual control to a
computer controlled milling machine
1 2
Photos 1,2,3 Various stages in cutting the rack.
A good friend was in the process
3
of acquiring a small clone of
a Bridgeport mill, the whole
bottom section of which had still
to arrive once lockdown transport
restrictions have been lifted. The model
is sold by Chester Machine Tools as the
830-VSR turret mill. An identical looking
machine is sold by Grizzly in the USA
under a different machine number.
He had already received the head.
The whole machine had previously been
used rather unusually as a CNC tool with
stepper motor drives controlling the
motions, including that of the quill.
Because of this the head was never
finished or equipped for manual
operation. In its new location my friend
wants to use it manually and while he
is more than capable of doing the work
himself, I was asked to undertake the job
of equipping the head in this new form. the aperture in the front of the mill. running and without any detectable
Also supplied was a rather slack. The bottom bearing, which
Extent of supply rudimentary handbook that also locates the vertical position of
The head of the mill was delivered to included an ‘exploded’ view of the the spindle within the quill, is held in
me with the head casting as one item mechanical features and a parts list position by a thick aluminium collar that
and wrapped separately was the quill to accompany it. These were in the screws into the quill on a fine thread.
with the R8 spindle fitted inside. There typical Far Eastern form which does The top of the spindle finishes in a
were no manual controls of any sort little else than provide names for the six splined shaft end that fits into a
for moving the quill. Two caphead components and where they appear in matching female splined drive coupling
screws in a milled flat on the quill the equipment. which runs in two ball bearings in the
were all that remained of the original The spindle runs in ball bearings head casting. The top, outer, end of
attachment for the stepper motor drive fitted to the top and bottom of the this coupling is fitted with a poly vee-
›
to the quill. It drove the quill through quill, they were of good quality, free belt pulley for the power input from
August 2022 9
4
The head casting did
at least have machined
mounting holes for a cross-
shaft, even though one had
never been fitted.
the motor.
The whole arrangement was well
constructed and business-like.

The new work
The head casting did at least have
machined mounting holes for a cross- Precision spacers
shaft, even though one had never been
fitted. These enabled me to locate the
5
centreline by fitting a ¼ inch diameter
silver steel rod through bushes machined
to fit, made from sections of cast iron
window sash weights.
Similarly, I made two plugs from thick
polythene sheet to fit the bore for the
quill, these aligned a second ¼ inch
diameter silver steel rod along the main
spindle axis. From these two references
I was able to measure the offset of the
cross-shaft centre line from the quill
surface with a fair degree of precision.
Using that information together with
measurements of the space available
within the head casting, showed there
was sufficient clearance to fit a 16 DP
pinion having no more than 15 teeth, on
a cross-shaft to mesh with a matching
rack cut into the quill.
I have done quite a lot of gear cutting Rack and pinion
in the past using my Tom Senior mill
6
but cutting the rack in the quill for this
job was at about the limit the vice could
hold and the machine accommodate.
Photos 1, 2 and 3 show various stages
in the work as it progressed. Prior to this
stage, I had removed the spindle to leave
just the quill for working on and taped
over the ends to prevent cuttings from
entering.
Very conveniently, the circular pitch
for 16 DP has a true value of 0.1963
inches which for this application can be
rounded up to 0.200 inches. Without
knowing really where the rack travel
needed to start from and finish at,
combined with the difficulties involved
in duplicating the operation for a second
time, it seemed only sensible to cut a full
length of rack using one setting.
The cross travel on the mill table is
The quill stop and DRO scale limited and it was all used by about
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