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Member postings for Zan

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

Thread: Pitch Circle
22/06/2021 10:00:11

As most drawings are produced by amateurs working in home workshops, and detailing what they have actually made the drawings are only as good as the skill of the designer in fully detailing ( or remembering ) any changes which had to be made as the build progressed. All drawings thus should be checked as far as possible for correct dimensions as it can lead to complications. I am making a loco donkey pump at the moment, using magazine drawings. The height if the pump block was given in its main drawing at 1/16” less than shown in the later drawing of the water passageways . This I missed this, so it gave me headaches to sort out, solved by making the top plate 1/16 thicker to make the block big enough for the stroke of the pump , but I still had another couple of mods to make to sort things out. The drawings for this loco build are tremendously accurate with tiny clearances and I trust them! It is essential as even with careful checking, a component assembly may have been made a long time before adjacent components are fitted, and mistakes in the drawings may not be spotted even with diligent care But as seen problems still arise. I suspect the problem this time was with the draftsmanship of the magazine employee rather than the designer.

if you make and measure where do you start? Something is needed to measure! It’s all part of the process as experience and knowledge of interpretation of drawings and the reality of construction grow. But it also needs common sense, you can’t drill holes in fresh air! Your case was a simple printing error . One of the advantage of producing 3D cad drawings is that the dimensioning is automatic to what has been created and such printing errors in both your and my case would not take place! But again, that depends on the designer actually doing that my designer does not use cad, and I am constantly amazed at his skill.

Thread: 2D and 3D Cad Software Recommendations
22/06/2021 09:18:52

Although the free version of 360 has reduced the availability of drawings ( only one drawing sheet per file), they are still possible within the 10 active file limit. It just mean a bit more work on the aspect of which file you keep editable

it takes a lot of effort to learn a new application even if you are familiar with either 2d or 3D cad, they all work differently. I now find fusion a bit frustrating, but i am certain it is still the best free system availiable

Thread: What lathe pointers
14/06/2021 16:02:21

If there’s 5000 members of this forum, there’s 5000 different answers. Every single person has different specific needs and space

Thread: Calculating Diameter
12/06/2021 17:24:20

First you need to decide the thread form whitworth or metric

then you need to determine the pitch if metric or tpi in imperial eg 10 tpi or 2 mm

then get some tables which will show you the proportion and the maths eg, pitch depth is .64 x pitch

then calculate the numbers from the thread profile data

too many unknowns at the moment except your stated diameter, but in wood, you will need a coarse thread to five any real strength

Thread: Can anyone help
07/06/2021 23:16:04

What’s the centre height? More info needed. What have you got? You say “another”

Thread: Taper due to tailstock height misalignment.
07/06/2021 17:55:37

Tom Walshaw, or George Thomas did a study of this about turning morse tapers and the usual advice to get the tool exactly on centre. I seem to remember that even a 10 thou error made almost no difference , units on less than 10th of a thou difference, and the conclusion was that the top slide dovetails would have more error

Thread: Master key - precision chuck.
03/06/2021 14:33:38

So so easy to find out. Just Chuck a piece of very round material. Tighten with each socket in turn noting the dti deflection. Remove bar, rotate it a bit and repeat.
it won’t take you long to find the best socket with the minimum eccentricity which can then be marker with an E for external. Repeat for internal with a suitable blank, and mark the socket I for internal.

if you want a more accurate test, repeat with different dia stock before marking.

 Not much faff, it will only take 5 mins

Edited By Zan on 03/06/2021 14:35:25

Thread: Myford extension for spindle.
31/05/2021 22:07:02

Would be very useful when using my Myford captain thus allowing use of the cross slide for cutoff on my short bed S7

Thread: Injector LBSC type
28/05/2021 19:18:55
Posted by Speedy Builder5 on 27/05/2021 12:13:32:

I have seen the terms 'bare' and 'full'

Bare is SIZE or just less and full is SIZE and a bit more. Looking at the injector here, the cone has to be a stiff push fit so that it doesn't move out of position (a force fit would be too tight for the "slotted cone".

SOD - If I understand correctly, injectors are a little "finicky" and those tight dimensions must be adhered to. having said that, those measurements were by eye from a rule !!

Bob

So once again, how much is just less or a bit more? Just as bad as full and bare 5 thou? 10 thou? 15 thou? 1 thou? I think dimensioning in this way goes back to the time of a combination of rulers, odd legs and callipers, and has no place in the modern workshop full of cheap digital equipment . It’s why our creations are so so much better in both fit, detail and interval between maintenance than in the past

Thread: Compressed air for initial engine test
28/05/2021 18:49:50

I think in addition, you will need a big diameter feeder pipe to minimise throttling

Thread: Injector LBSC type
26/05/2021 18:12:25

All my jubilee injectors have only one cone in the centre and they work fine , in place of both the small centre ones. In addition it should be noted they also supply a lot of the trade.

 

 PS. what  is 1/32” bare? It’s not on my ruler or micrometer. Is it -5 thou?  -10 thou? or whatever. so why not just give the actual dimension

Edited By Zan on 26/05/2021 18:16:37

Thread: Lathe run out
10/05/2021 18:59:37

“not bad for a rusty old bar of 1" cold rolled.” So did you run the dti all along the bar at the front and on the top? Bet it won’t be held true in the Chuck and it will probably be bent accounting for the difference and this bar even if short  will not be held true due to the rust and  rolling tolerance, it’s not an accurate material 

is the runout you quote on the rotating bar?
As said above you need tailstock support and a travelling steady

have you done the standard bobbin turning test to check for any bed twist?

have you done the between centres test to check the tailstock position?

moving the headstock will not be easy due I think it being sat on the v ways on the bed

tread slowly!

 

Edited By Zan on 10/05/2021 19:01:31

Thread: Myford Super 7 Toolpost issue
07/05/2021 14:10:31

I use 8 mm tooling and have reduced 1” to nothing in two cut,s, but it’s pushing the machine too much, and was just about seeing what it could do. Now I would use use three The 7 series are small lathes and don’t warrant anything bigger. I use exactly the same tooling in my Colchester student without much problem with decent sized cuts

07/05/2021 14:10:30

I use 8 mm tooling and have reduced 1” to nothing in two cut,s, but it’s pushing the machine too much, and was just about seeing what it could do. Now I would use use three The 7 series are small lathes and don’t warrant anything bigger. I use exactly the same tooling in my Colchester student without much problem with decent sized cuts

Thread: I dropped it
06/05/2021 19:16:08

Well at last I realised how to stop me bridgeport quill from tightening when drilling and making things stiff and loosing sensitivity. The spring clip which used to be used got in the way n I had a brainwave. Fit a spring washer! Remove lock and find it’s a pair of shaped collets. Oh a very light spring will do the job between the collets.

find long soft spring. Stand in front of machine and cut flat end off and chop a short length. Put it in position.. it works. Brilliant

where’s the spring? Must be on the floor, I’m sure I saw it fall. Grrr not again....

out comes the torch from me pocket where it lives to direct the spring hunt

on me knees yet again. ( perhaps the third time today) hunting fir the spring to put away.
new brainwave. And the request. I need a Heath Robinson type of inventor to design and patent a raising floor I press a button, or wind a crank to raise the floor up to waist level so that I can pick up the frequently dropped item without having to get on me hand and knees with all the problems of getting up again.

any offers?

ps I didn’t find the spring

found an hour later sat in my overall pocket where it was caught by the gremlins.

Thread: Which type/brand of razor blades stay sharp longest? (cutting card/greyboard)
28/04/2021 00:10:14

Eze lap diamond hones. Availiable from many places on line  I used the red 600 grit, had it a long topime didn’t know if it was still available but just found out it is and about the superfine at 1200 grit  .....must get one!

Any cutting tool including kitchen knives which reflect light and the edges shine are blunt it’s the easiest and most common test Nothing as sophisticated as a samurai sword All edges are rather same, including milling cutters and lathe tools. Esp hs

Edited By Zan on 28/04/2021 00:22:02

Edited By Zan on 28/04/2021 00:25:34

Thread: Milling Feed Speeds.
27/04/2021 19:06:00

Sod, interesting. Your depth of cut seems a bit shy, but the rpm=. 10000/ cutter dia gives 1666 rpm, the presto data for slot drills gives 1592 rpm - very close. - with a feed of 0.023 mm per rev but only 73 mm/min . So your figures give a very good speed basis
for a 10 mm cutter, yours, = 1000 rpm, presto 955 Feed 92mm/min So your easy calculation is sound, but gives a speed just a bit too high

the recommended depth of cut is 1/2 diameter (slot drill diameter for end mill) but that of course depends on your machine. No probs in my Bridgeport, but too much for my Sieg sx2+ cnc conversion


my numbers refer to an HSS cutter, for carbide, the numbers would be  3988 rpm   With 0.038 cut per tooth  = 285  mm/min.   So it seems the op quoted numbers are a quite a bit on the high side! As I also have seen from the vendor

Edited By Zan on 27/04/2021 19:26:29

Edited By Zan on 27/04/2021 19:30:32

Thread: Tormach style tool holders
27/04/2021 15:31:05

8e04841c-83dc-4002-86ab-7bcde086b530.jpeg
 

Grrrrr.  my photos are always upside down. After uploading No good. Deleted it from album, I rotated this upside down in my library and re uploaded it .... still upside down! How do I solve this?

Back to the subject.

The setting jig is a cheap calliper cut down and bolted onto a secured packing block to bring it to centre height. The tool is fitted (after zero in the caliper against the block) into an accurately machine 3/4 inch diameter hole in the cast-iron block. The offset is those directly shown on the calliper. In Mach 3 the setting tool is listed as being 115 long and is designated as Tool number one in the listing. To use insert the setting tool and jog down until the dial reads zero then simply the z axis. The tool shown in the photo is simply put into the appropriate position in the Mach 3 tool table and set up as being a length of 55.21mm as seen in the photo this enables it to be permanently set to a length and does not need checking again it is a very simple and robust system and is based on the Tormach method

The   top photo shows my full tool drawer I did make it for 1/2} and 12 mm tools, but experience has shown these are very rarely used, and I intend to experiment with converting these to 6 mm and smaller, which is the range most often used, and at the moment my spare holder is getting too much use!

In  the tool table, a 6 mm carbide cutter is found as tool no. 60  listed as  “6 slot cab 6A “  The 6 a refers to the tool position in the drawer   Drills start at tool 100 so a 2 ba tapping drill [4.1 mm) is tool no 141    While  a 10 mm is listed from tool 10 , 8 mm from tool 80 etc  the 70’ s are used for special use   A printout in a grid enables values to be recorded in pencil to allow changes and be used in the office

this system makes it easy to switch between the desktop in the office where Fusion 360 sits and the off line  workshop 

92d8bb92-f5ab-437d-8196-3c276dcc7f4b.jpeg  

Edited By Zan on 27/04/2021 15:42:58

27/04/2021 14:50:49

For my cnc mill I use a 3/4” silver steel slug very carefully centred in a collet, then drilled and reamed fir the cutter

the cutter is locked in place, then put into the R8 collet in the mill and tested to find the best position for minimal eccentricity tested on the Miller shank. Usually, there is less than 0.5 thou error. The holder at the very front is marked and removed from the machine for fitting a 7/32” silver steel pin pressed into a part reamed holedrilled at the front position . This controls the tool extension for adding into Mach 3 and thus the cutter orientation is always in the same position.

0771fc09-5631-489a-b841-0813b391ca05.jpeg
 The pin locates onto a collar machined in situ on the spindle, used as the R8 collet does not have a flat face  the drilling seen indicate where to locate the pin  on the spindle collar 

the height is set using the dti device which is set to exactly 115 mm  using a setting jig   I’ll add a photo later of this in action  

my sx2+ Miller runs at 3400 max speed  due to changing things in the conversion, al detailed in a long series in ME about 4 years back  I haven’t noticed any vibration problems 

 

369b6496-7ffe-4a43-a93c-2917dab55034.jpeg

Edited By Zan on 27/04/2021 14:58:07

Thread: Boiler barrel
27/04/2021 14:18:50

Paul So u would need a barrel at the diameter of the smoke of size meaning a reduction of size and water capacity at the firebox cleading  would still need to be tapered for correct appearance and possible problems with top feeds ad s valves

I understood the taper was about improving water circulation and reducing the diameter of the smoke box to allow even a short chimney to be within the loading gauge. Plus various other thermal issues

edit...l blasted autocorrect!

 

Edited By Zan on 27/04/2021 14:20:31

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