Here is a list of all the postings DC31k has made in our forums. Click on a thread name to jump to the thread.
|Thread: ER 40 Milling nose|
Have you considered how you will hold Morse tooling in the new spindle arrangement, particularly drill bits?
I have never drawn it up, but what size Morse taper would fit within the confines of the ER40 collet cavity?
|Thread: Brierley ZB21|
There is also a ZB25 manual available at a price much more commensurate with its quality on eBay. The seller is fazerblazer and full seller contact details can be seen without logging in - Premier Machine Tools in Nottingham.
As for the cams, they are fairly easy to duplicate if you can find someone who has one to copy. Just put on a rotary table and map the rise every couple of degrees of rotation.
Find someone with a CNC machine with an A-axis and a touch probe and the mapping could be done almost automatically.
AFAIK, the 21, 25 and 32 in the model name referred to the biggest tool that would fit through the spindle. In most other respects, the machines were the same, so a manual for any will do.
Tony at lathes.co.uk sells badly-photocopied incomplete manuals with thumbprints and distorted pages but on very good heavyweight paper.
You could look at this:
or look here:
|Thread: Stuck SDS drill bit|
The diagram in the article to which Michael links is very useful:
The (normally rubber-like) end cap, not numbered in the diagram, but cut through by the upper and lower II section arrows, should just prise off. This will allow access to the collar that retains the balls.
As he says, a good clean and lubricate should solve your problem and endcap removal will allow you to check that the collar is retracting properly. The balls have to come out from the outside or they would fall into the chuck every time you remove the bit.
I have only seen it once before, and I hope it is not the issue here, but I once had an SDS drill bit that was improperly heat treated such that the hammering action mushroomed the end of it within the chuck. This made it very difficult to remove.
|Thread: Type identification of a endmill tool holder|
M. Georges Savoie must be feeding his hens something special then:
|Thread: Strength of Beams|
I am glad that people are slowly coming to the conclusion that the question is unanswerable as posed.
For a given area of material, anything other than a regular shape (circle, equilateral triangle, square, etc.) can be made to have an almost infinite second moment of area.
Take the I-beam, for example. I read that gold can be hammered to 4 millionths of an inch thick. So use 1% of the material to make a web of this thickness and divide the rest of the material between the two flanges.
Totally impractical as a real-world object but fits the question very well.
A little thought on the first example given in the original post would show the form of the question presents difficulties.
You do not need to be Superman to deflect a rectangle on edge. Take a ruler and try it. Press not too hard and it will buckle out of the plane of the applied load. And that is the problem every real-world engineer has to face. Pushing on things in one way induces forces and effects in another.
A more simple example is compression. Intuitively, why would we expect a structure to behave much differently when we squash it as opposed to when we pull it apart? But it does. And this has been known since Euler's time.
So when we bend something, we have both tension and compression (and anyone who has ever cut a branch of a tree will know this) and the member subject to bending will inherit some of its behaviour from both of these.
It is horses for courses.
The traditional ones give long spans for efficient material use, good for single-storey warehouses and industrial buildings.
However, when it comes to multi-floor construction (office space), the circular ones are much more popular. They allow the myriad of building services to pass through the holes in the web rather than under the bottom flange. This means the overall structural depth can be reduced, allowing more than one extra floor (with its per square foot rent).
Where rectangular holes are needed, they can be incorporated, usually with stiffener ribs above and below the opening.
The march of technology has also had an influence. Traditional castellated beams were cut out of pre-existing rolled sections. Most modern cellular beams are cut from three plates and welded together. This gives you a lot more choice on both flange thicknesses and widths and also web height. CNC profiling and automatic welders facilitate this.
I thoroughly endorse your recommendation of Gordon's books.
Not only do they deal with traditional engineering materials of concrete and steel, but also give very good accounts of building in stone, as well as interesting discussion of nature's own building materials, wood, bone and sinew.
On the 'computers' issue, applied to the US space program, the book 'Hidden Figures' is very good.
|Thread: Change gear alternative material|
If you do go the Tufnol route, be sure you understand the different fauna under which it is sold (e.g whale, carp, etc.). For gears, you will need the type that is made like plywood, not the type that is made like a Swiss roll. There has been discussion here on this issue relating to Myford tumbler gears.
I do not know if it allowed now, so read this before it is moderated: there is a UK-based eBay seller with the username of you_engraving who makes various change gears in delrin at very reasonable prices. With Colchester gears, it is often the centre spline that is more difficult to make than the tooth spaces.
|Thread: Left Hand Milling Cutter|
Would it be possible to do something to the mandrel to increase its holding force?
There are lots of solutions to stop Myford chucks unscrewing when the lathe is used in reverse.
Schaublin W-series spindles use a split clamp to secure the threaded-on chuck.
Look at how the track rod ends are clamped on your car.
|Thread: Boring bars|
The rigidity of the bar is governed by two properties: the second moment of area (I-value), a geometric property, and the Young's modulus (E-value), a material property.
So which of these change after hardening please?
|Thread: Split collet steel recommendation|
The only time I have managed to hacksaw at this speed is as a passenger in a van on the motorway.
|Thread: DIY Rotary Quadrature Encoder|
For the purposes of understanding its operation, I wonder whether it is helpful to draw the analogy between this device and some linear scales (Heidenhain and possibly Newall) that use a (n analogue) sinusoidal output instead of a quadrature pulse. The scales will resolve 1 um.
One big advantage of this sensor that struck me overnight is that it can be made into something with a very small length. If we have the end of the shaft as datum, all you need is the magnet thickness, the air gap, the chip height and PCB thickness.
I was dreaming of something that would go under my compound slide and feed into the DRO in the same way that a knee-quill adder box does on a mill.
The crux of it seems to be on page 10 of the datasheet.
The Hall sensors give a continually varying analogue output.
This is amplified, then goes through an A to D converter and then there is an inbuilt CORDIC that calculates the angular position.
I guess that for every 'tick' of the encoder, there must be a unique set of four values from the Hall sensors.
The headline cost of $10 seems good but how much value does the time to make the PVC housing, the magnet and PCB consume? And compare that to a 1024ppr encoder available from a source, which will be moderated if mentioned.
|Thread: Welder buy|
That is a good link and perusal of it may help to dispel some of the misinformation above your post.
Perhaps its parent link, BOC's guide to shielding gases in general, might be even more instructive:
|Thread: All things Beaver Mill|
It is on the handle side of the head.
post by Paul Major 09/02/14 23:03:40, sixth photo of post.
The spring is inside the left hand gear.
|Thread: Harrison M300 - am I going crazy?|
It is quite rare for the carriage handwheel to be graduated.
Some high end machines and clever manufacturers do it but it is not the norm.
The reason is that the the apron moves due to the action of a pinion on a rack fixed to the bed. For the wheel to have sensible graduations, the rack would have to be of circular pitch specification (i.e. its teeth some easy rational number of chosen unit apart).
For length measurement without DRO, a (micrometer) bed stop and spacing pieces can help. I believe Harold Hall published something on this, so check his website or early back issues.
Another option, liked by the Myford brigade, is a graduated wheel on the end of the leadscrew and use that with the half nuts engaged.
Edited By DC31k on 02/09/2020 11:30:22
|Thread: Harrison M300 Apron|
Go into back garden.
Cut stick from hedge.
Whittle it down until it is the same diameter as the shaft you are removing.
Insert from opposite end to which you are removing shaft.
|Thread: UK availability of 1/8" Dia shank End mill/Slot drills|
What you are looking for is difficult to find in this country. If you can relax one or both of 1/8" and HSS, you may have more success.
3mm shank carbide is the nearest-easily-available over here.
One specific size, 1/8" dia. 1/8" shank, is not too difficult to find, but smaller sizes are not at all common.
Peatol sell small imperial HSS cutters but they are 3/16" shank.
If you have to have what you want, and have any American friends, MSC sell them:
|Thread: Change to the Code of Conduct|
In the interests of properly following your own CoC, should you not blank out the logo on the drinks-can-for-scale as it may imply endorsement of a non-forum-funder's product?
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