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Member postings for John P

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

Thread: Super 7 stiff feedscrews
28/10/2021 08:26:48

Hi ,

Sound as if you are having similar problems to the Myford lathe in this posting https://www.model-engineer.co.uk/forums/postings.asp?th=173467 , all routes lead back to RGD.

 

The conclusion  was  on this posting  was

"An update, Myford suggested I return the screw and nut for appraisal, which I did. They detected tightness and suggested it was borderline on tolerance and sent a replacement "original" Myford screw and nut which I fitted today. The replacement is significantly better but lacks the silky smooth action of the metric screw and nut. I can't get it down to virtually nil backlash either.

I am reluctant to concede that it may bed in as I feel it should work out of the box."

Perhaps they just stuck the old one back on the shelf  for re sale!

I don't bother with such things now i just make my own  they work every time that way.

John

Edited By John P on 28/10/2021 08:32:44

Thread: Mill table wonky
27/10/2021 22:01:25

Hi Steve,

Yes those three holes , it would be as well to assemble the parts as suggested earlier just to check the positioning before drilling the holes in the end of the table as if any of the the existing positioning is off it will lead to an error.

(because the ****** person who built the mill) as you had written earlier had obviously got some things wrong like having the table the wrong way round.

John

27/10/2021 21:07:21

Hi Steve,

just as a postcript to the previous posting that i made be careful about following the drawings as it appears from the third photo down on your posting at 10:34:11 today that the 3 holes that hold the leadscrew nut may also not be in the correct position , that extra little cast in lug on the XY slide is for that third screw ,as far as i can remember the tapped hole sits more to the left and a little higher in that position.Would be worth checking before drilling any holes.

John

27/10/2021 20:32:26

Posted by Steve 355 27/10/2021 14:07:24

Now I’ve just got to work out how to drill accurate holes in the end of that table.

Luckily I have a big pillar drill!

The easiest way to do this is to remove the XY slide from the machine,
lay the table upside down on a bench fit the X leadscrew nut in position
on the XY slide fit the XY slide on the table fit and adjust the gib in place ,
screw in the leadscrew and end bracket as far in towards the nut as it
will go ,if you view down alongside the table the leadscrew should be
visable and it will be easy to see if the leadscrew is parallel with the
slideways then looking down from the top likewise the leadscrew
will be in line with the slide bars.
Probably easiest to just fix the end bracket to the table with a dab of epoxy
glue let it set ,make up a long centre punch that fits in the holes of
the end bracket ,if the glue will hold you can carefully traverse the
XY slide along the table before marking the 2 hole positions to test
the position.
When satisfied with the positioning use the punch to mark the
hole positions drill and tap for the 1/4 bsw fixing screws if they are
still this size they are on mine.

John

27/10/2021 13:27:56

Posted by Steve 355 27/10/2021 10:34:11

Is this statement true? :- It doesn’t matter if the milling table is not square to
the base of the mill (within reason). The milling cutter is round. What matters
is that the X, Y and Z axes run perpendicular. Tramming ensures the Z axis
is perpendicular. The X and Y axis should be perpendicular by
manufacture of the table.

Yes it is true , except for the last part after i had built my Dore westbury
the squareness of the X and Y was off by few thousanth's of an inch,
it is possible to re-machine the Dore westbury XY cross slide on a Myford 7
lathe cross slide because this is how i corrected mine.


There is little point to having the tee slots in line with the travel of the table
because of, 1 the longitudinal slots at each end are too short in all probability
to be able to mount any additional accessories (vice) without using some of the
other slots in either side of the table ,2 the tee slots in a Dore westbury are cast
in and not machined and are useless as a reference unless reworked
for that purpose.

As it is the 1st photo that you have posted showing the underside of the
table the dowels are in the correct slideway/ guide ,as you have surmised the table
has been fitted the wrong way round, however fitting the table as in the last photo
which is the correct way round also puts the guiding slide with the dowels on the
correct side, it is worth noting that if you remove either of the 2 guide strips from the
underside of the table they may be shimmed as this is the normal method on these
machines to control the table lift /clearance.

John

Edited By John P on 27/10/2021 13:35:41

26/10/2021 22:16:32

If the edge of the table is not parallel to the direction of travel which seems to be what you are saying here, it is not anything to do with the slide way strip that you have shown in the photo with the caliper reading of 2.973" .The guide strip that is screwed to the underside of the table the one the gib strip runs on controls the position of the table ,you would need to check that the guiding edges of this strip are in line with table edge.

In any event apart from from a nuisance does not affect the operation of the machine in any way ,for what it is worth you would probably need to replace the strip rather than try to reposition the countersunk holes any distortion to the existing strip is likely to lead to more problems.

John

Thread: The Interesting Video Thread
24/10/2021 10:07:37

If you have half hour spare watch this video on building a home made lathe.

https://www.youtube.com/watch?v=z67A3Myy6XM

John

Thread: Wandering mill table
23/10/2021 11:03:26

That looks as if it is ok as noted previously by Journeyman , have you checked also the gib strip adjustment on the Y axis slide way, try the test with the Y axis lock tightened.

John

23/10/2021 09:14:51

Bit a of a long shot this its 40 years since i built my Dore wesbury mill, the two steel flat bars that are fitted to the underside of the table one of which provides the narrow guide for the gib strip to run on and sit under the two steel strips which form the bearing surface for the table to traverse on ,all of these strips of steel are attached with countersunk screws ,the guide strip should have a a couple of hollow spring dowels to secure the strip to the table .It may be worth checking if the guide strip that is fitted to the underside of the table is still secure and the screws are still tight as if the strip moves about the table would wobble as you have described.

John

Thread: Myford ml7 "parting off"and "max working size"
22/10/2021 12:53:46

Wash the drive belt and pulley's with paint thinners dry off and get some belt dressing spray (Rocol) it will help with the belt slipping problem for a while until the belt gets contaminated with oil again ,have similar problems with my super 7.

John

Thread: Spacing of buttons for making involute cutters
21/10/2021 18:43:23


Button form tools used on the Eureka device can be a problem
to make in the sizes above cutter No 4 the radius is so large
that it would interfere with the body of the device , see here the photo
of 6 off 20 DP 20 pa cutters and tooling to make them .
Only a small part of the circle is needed to form the cutter in the
sizes 3 to 1.

eureka 1.jpg

These illustrations taken from an old book shows how this used
to be done and may be of some interest especially if you have
a shaper ,i don't need to add any more the pages show it all.

John

relieving1.jpg

relieving2.jpg

relieving3.jpg

Thread: cutting spur gears on a mill
08/10/2021 09:42:46

Posted by Jason B 8 10 2021 07:15:50

Brian Wrote

"I wonder what DP Myford gears were made to? They look crude and square CI to me at first glance must examine one closely. I stole a spotty neighbours kids USB microscope (Bresser) and it provides very usable pix at 20X on my PC screen, at 80x I can even see little living amoeba in our pond water, maybe grow some tardigrads"

Why on earth would you need to go to the trouble of using a microscope to find out the DP of Myford gears?

With all the links to various gear calculation charts in this thread etc You should have no difficulty in working it out all you need is OD and number of teeth which should be easy enough to see and in most cases give you a usable answer. PA has also been mentioned here and probably DP too. This is the way a beginner with limited resorces can work out gear sizes I would have thought that would be right up your street.

Hopefully beginners have learnt from this thread but from your methods to work out the DP of Myford gears you certainly have not picked up much useful information and it is no wonder you have not been able to come up with 2:1 gears yet as it's these every things that need to be understood to be able to design simple gears.

Edited By JasonB on 08/10/2021 08:07:40

================================================

I just wonder who that this reply was aimed at as all of Brian Jones 11 's postings seemed to have disappeared from this thread ,shades of Barrie Lever .I thought that the posting that you put up in Home cnc the other day here

"From Previous posts on here the Wabeco machines seem to perform well, have a look back for posts by barrie Lever. "

was bit daft as all of his postings have been removed and is only referred to as Former member.

John

Thread: gr 8.8 ht bolt steel which carbide tip
06/10/2021 20:00:40

Here is an 8.8 bolt head faced off by hand with a 23 pence tip from Ali******s ,one real difference that you can positively identify from a £5 one is £4.77 in change.

John

23 p  tip.jpg

06/10/2021 16:22:58

Posted by Brian jones 11 06/10/2021 15:24:33


obtw I think Ive been down this road before but it seems EB is utterly flooded with
PRC offers of complet???? sets of tools and inserts most of which i dont want

AFAIK you cant buy individual tool holders like I want 3 for lh rh centre for a
triangle insert say and 10mm (not the more popular 12mm

any suggestions - how i hate abusive EB pursuing profits before public
benefit - where have I heard that already

Brian

Hi Brian,

I buy my cutting tips from Ali*****ss the last set i bought were
CCMT 060204 VP15TF Mitsubishi they are only £2.30 for a box
including the VAT and free shipping for 10 tips and are as good as any
tips that i have had over the years .
If you look around on that site the tool holders are there for probably
less than £8 each.
I can't put up the part numbers on here as they will be taken down, if you
want them send a PM and i will send back by return.

John





Thread: MES Kennett tool and cutter grinder
04/10/2021 19:36:17


The Kennet much like the Quorn grinder has about the most
useless wheel guard you could imagine ,since building
my Quorn grinder about 36 years ago although i made and
finished the guard i have never used it ,the access when
grinding tools with a guard fitted is so poor even if you do
make a guard is such that you will also most probably
never use it , invest in some face covering and protection
don't use the machine and stand in line with the wheel when running
and above all don't let anyone else use the cutter grinder .
Used sensibly the wheels will last a very long time i
still have all of the original wheels that were supplied with
the kit when i bought it .
If you intend to go the diamond wheel route Alie****ss
do several variations of nickle plated wheels which are ideal for use
on the Quorn or Kennet ,there is no point in giving the part numbers
here as they will only be removed.

John


 

Edited By John P on 04/10/2021 19:37:43

Thread: cutting spur gears on a mill
28/09/2021 10:06:33

all alone.jpg

Thread: Turning (approximating) a Domed Surface
27/09/2021 18:52:30

Just found this photo re my last post showing

set up for turning small radius.radius turn.jpg

John

27/09/2021 18:44:59

Posted by Dr_GMJN 27/09/2021 16:30:39

All,

I need to turn a dome shape for a pair of cylinder caps. Similar to a typical
smokebox door kind of thing.

I've heard of using co-ordinates on the cross and top slide,
presumably in conjunction with turning the top-slide to different
tangent angles. Can anyone tell me the procedure, and also what's the best
way of smoothing the facets generated? I want them to be identical.

Material is cast iron. Radius of the dome is about 50mm, and
the diameter of the domed disc is about 25mm

Thanks.
----------------------------------------------------------------
The easy route to turn this type of radius
is to use fixed length rod the radius you need
with point on each end and one fixed place
on the lathe bed for one end of the
radius rod and one fixed place on the crosslide
for the other end see sketch.

turning radius.jpg


In use some pressure is applied with the carriage
feed handle to keep the rod in place.
With the tool tip on centre the radius rod is parallel
with the lathe bed,as the crosslide is moved out the
pressure applied to the carrage feed moves the tool
in the required radius,depth of cut is applied via the topslide.

John

Thread: cutting spur gears on a mill
26/09/2021 11:28:49

Posted by brian jones 11 25/09/2021 15:48:26

Looking at the Crown and bevel pinion, without the
benefit of CNC how does one make those pieces

---------------------------------------------------

It would be worth Brian getting a copy of
Gears and gear cutting and reading through it.
Making parallel depth bevel gears is not that difficult
if you follow the the instructions in the book.


I have made several sets of parallel depth gears over the
years ,if you set up and mark the centre they can be done
in just two passes ( which would obviously please one
particular poster on here ,or maybe not).
I had always been a bit skeptical as the the long term use
and how much power they would transmit until the last set
that i made.
Material selection is obviously of importance ,so a rummage
around in the scrap box and a couple of likely rusty candidates
emerged.
The job was a pair of gears to replace the stripped bevel gears
in a detail sander (Wickes).
I was unable to get the exact tooth count of the original gears
but the gears that were made are close enough.
The cut gears were lapped together for a while with some
Timesaver green label fine abrasive, cleaned and sandblasted
then soaked in some Kasenit in a sealed tin for an hour .
Here is the finished job ,the pinion runs at about 18 to 19000
rpm and surprisingly reasonably quiet.

detail sander.jpg


I wonder if Brian has looked in at this forum post and the link
to this amazing piece of work.
Do you think that the gears have been
cut one tooth at a time
https://www.model-engineer.co.uk/forums/postings.asp?th=174884

John




25/09/2021 19:44:03

Posted by brian jones 11 25/09/2021 19:21:37


What astonishes me JP that in this day of unbelievable high tech gadgetry at such
low cost, we havent seen a means of laser scanning the gear you showed in your
pic above cos thats the degree of measurement needed. Feed the data into an
app and get a best estimate of what you have.

After all thats what the big boys do when making big gears, they measure to
microns across a diameter of 10 meters

thats cooking on gas

-------------------------------------------------------------------------------------

The micrometer was only £25, i guess that your eyeball
measuring system of measuring PA has failed on this
occasion.

Gas supply failure!

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