Drawing Quality

[Robert Miller 1Participant @robertmiller1]

[q]Im new to this game. Was wondering if any one could tell me if auto cad 2009 is compatable with microsoft paint as i have some drawings on my computer that i want to try and load into my hurco CNC machine.[/q]

Since nobody else has answered your question, I’ll try but I have no direct experience with AutoCAD as I use TurboCAD, so take my words with a grain of salt.

Drafting packages like AutoCAD are vector drawing packages. That is, the information is stored as descriptions of lines and curves. This allows the images to be scaled and manipulated relatively easily. Microsoft Paint and other similar products are pixel based so a line in paint is described only as a number of adjacent bits of the same colour. The two are not directly compatible.

However there is hope, what you need is a raster to vector conversion package. There are a number of these on the market (Googling bitmap to vector conversion software will point you to several such), but I haven’t used one in years, so I can’t make any recommendation. The last one I used was part of Corel Draw possibly ten years ago and the output from it took a lot of editing before it was of any use in a drafting package.

That said, it is possible that AutoCAD incorporates such a package as an import filter or bundles one with the distribution, but I really can’t say. Maybe there is an AutoCAD user here who knows.

Bob

[Grahame Chambers 2Participant @grahamechambers2]

Posted by Jeff Dayman on 23/10/2011 14:08:08:

In MEW 181 I read the article on pgs 24-24 by Mr. Santafe for his micrometer holder. A nice little tool. However the drawing for the micrometer holder part shows dimensions which will result in a zero wall thickness. The 8mm dia hole is shown at 21 mm from centre on a 25 radius part. (Also, the hole should probably be 8,1 or 8,2 dia to pass an M8 screw. ) There are several simple ways to remedy the wall thickness before cutting metal, the 21 mm dim could be 20, or 50.8 mm stock could be used, or a smaller M6 screw and 6.2 hole could be used. A minor point but a notable one for draughtsmen is that a round part should have the OD called out as a diameter, not a radius. (He makes the same mistake again on pg 57 in fig 6 for the clamp screw detail of the topslide article).

 

In the same issue there is an article on pgs 30-31 for a tangential flycutter. Again, a nice little tool and cleverly made. The drawing of the base plate however is poor. The chosen scale results in views far too small to plainly show the details, and clamp screw hole location dimensions and the slot angle dimension are not shown.

 

A poor job in MEW 181 by the illustrator.

 

JD

 

I’m the illustrator but I’m not an engineer – if diagrams are supplied as CAD I resize them to suit the magazine layout, adjust the line weights & change the font. Otherwise, I redraw what is supplied, before they’re sent to David to check. I then make any corrections he asks for & the diagrams are sent to the magazine designer.

 

Concerning the micrometer, the hole position etc. is as supplied by the author.

 

Concerning the flycutter, the dimensions & angles were not on the author’s original supplied to me. The size of the diagram is dictated by the amount of space available in the article.

 

Thanks

Grahame

[Jeff DaymanParticipant @jeffdayman43397]

Grahame,

 

Excuses don’t cut it. I learned that very early on in industry. When I made errors the best received action by users and bosses was to make the error known to those concerned, and publish a corrected drawing ASAP.

 

There is NO excuse for unreadable drawings because they were scaled too far down. Larger scale detail views can be used if there is not room to show the whole item.

 

For holes where no dimension is known, a note saying “locate hole from job” or “location of hole to suit fastener” would suffice, rather than nothing at all.

 

Outside diameters should be noted with diameters, not radii.

 

JD

[Grahame Chambers 2Participant @grahamechambers2]

Posted by Jeff Dayman on 31/10/2011 14:47:01:

Grahame,

 

Excuses don’t cut it. I learned that very early on in industry. When I made errors the best received action by users and bosses was to make the error known to those concerned, and publish a corrected drawing ASAP.

 

There is NO excuse for unreadable drawings because they were scaled too far down. Larger scale detail views can be used if there is not room to show the whole item.

 

For holes where no dimension is known, a note saying “locate hole from job” or “location of hole to suit fastener” would suffice, rather than nothing at all.

 

Outside diameters should be noted with diameters, not radii.

 

JD

 

I’m not making any excuses, I’m simply explaining the situation. Perhaps the points you raised will be taken into account & corrected diagrams will be published, but that’s not up to me.

 

Thanks

Grahame

 

[Jeff DaymanParticipant @jeffdayman43397]

according to Webster / Merriam dictionary:

“Definition of EXCUSE:

transitive verb

1a : to make apology for b : to try to remove blame from “

 

Your original post sounded like a lot of item b above.

 

JD

[Peter G. ShawParticipant @peterg-shaw75338]

Hi,

 

On re-reading the original, and subsequent requests, and cutting out all the less than helpful replies, it does seem that some people here are in the same postion that I was in 20 or so years ago. Not that I am that much better now, but I can offer suggestions based on my own experiences as a rank amateur.

 

First of all, it is not that you have too much information, since there can never be enough, it is more that you have not got any information relative to your situation, ie as a beginner. In this respect might I suggest that what you need is not books written by engineers for engineers, but books written for beginners and here I am going to recommend an old book – “Using the Small Lathe” by L. C. Mason. This book discusses most of what some of you are asking, and as a friend of mine said after he had read my copy “it is written by someone who understands the beginners problems”. As is usual with me, I would suggest seeing if your local library can obtain a copy, although the book isn’t really that expensive.

 

I would then suggest that reading some of the books Tubal Cain and Harold Hall, titles such as “Workholding in the Lathe”, “Drills Taps & Dies” and as someone else has said, “Workshop Drawing”, all by Tubal Cain who in his day was a highly skilled designer and who has the knack of making things seem simple. From Hall, “Lathework, A Complete Course” might be a good idea.

 

There are other writers who have written books aimed at the beginner, but in my opinion some of these are rather too simple and don’t really supply much basic information, whilst others possibly attempt to cover too much detail and end up leaving some questions unanswered.

 

Then there are writers such as Geo Thomas and his “Model Engineer’s Workshop Manual”. This book assumes you have a Myford Series 7 and assumes that you already have engineering knowledge. In my opinion, this book is not suitable for a beginner. Similarly Sparey et al.

Above all, you need to read, and then try it out on scrap material – you will soon find out what works for you, and just as important, what does not work for you. You will also find, and I expect to get shot down for this, that the digital instruments are not as good as they are cracked up to be, certainly the cheaper ones aren’t – I cannot comment on the likes of Mitutoyo and that the cheaper carbide tools are not much use for the amateur on a small lathe. The result is that for me, I have reverted to the old-fashioned dial calipers and micrometers, especially as I have been able to compare measurements and thus know what differences to expect, eg a nominal 25mm can be, depending on the instrument, anything between say 24.995 to 25.005 mm, last digit estimated by division splitting, something you cannot do on a digital gauge. In respect of carbide tools, I am slowly reverting to HSS, carbon steel or even old files cut up and reground into lathe tools – I have a parting off tool made from an old ½in x 4in file which works extremely well.

 

Regards,

 

Peter G. Shaw

 

 

 

 

[Grahame Chambers 2Participant @grahamechambers2]

Posted by Jeff Dayman on 31/10/2011 15:31:56:

according to Webster / Merriam dictionary:

“Definition of EXCUSE:

transitive verb

1a : to make apology for b : to try to remove blame from “

 

Your original post sounded like a lot of item b above.

 

JD

 

You’ll also find this definition:

 

“To explain (a fault or an offense) in the hope of being forgiven or understood“

Which is what I said.

Thanks

Grahame

[David LittlewoodParticipant @davidlittlewood51847]

Peter,

 

I was (mostly*) with you until the last paragraph. However, having myself fallen into the trap, when a complete beginner, of practising on bits of scrap found from random sources, I don’t think that is advisable. Some lumps of steel of unknown provenance turned out, for me at least, to be horribly stringy stuff; it was only when I started using decent free cutting mild steel that I discovered what a pleasure it was to turn.

 

Also, being of the age where my eyesight is no longer as youthful as it was, I find digital calipers a great benefit. I doubt if there is much work done by amateurs where a resolution of better than 0.01 mm is required – and it it is, a micrometer with a “tenths” vernier scale is probably more accurate than trying to interpolate on a vernier caliper.

 

Finally, I also believe tooling with interchangeable carbide tips to be a great benefit, and this is espacially so for beginners. Using them avoids the need for grinding accurate angles on lumps of HSS, often after removing vast quantities of material; doing this on carbon steel is very difficult without overheating and losing the hardness. As one gets more experienced, or maybe when one acquires a proper tool grinder, then the use of HSS and CS becomes more feasible (but still mostly for tools not available commercially IMO).

 

*Oh, and I belive that even if you don’t have a Myford, the GHT books contain a vast amount of invaluable guidance. You do need to know some of the basics, but if you make even a couple of the items of tooling therein you will no longer be a rank beginner.

 

David

[Steve WithnellParticipant @stevewithnell34426]

I believe that you do need to develop a reasonable level of skill in grinding on an off-hand grinder, unless you have the space and cash for a tool grinder. In any event, there are situations where a job needs a custom lathe tool often enough to be valuable to develop that reasonable level of skill. Most often I use silver steel rounds. I do use carbide tipped tools too for straight forward turning, but they are expensive for a one-off job.

 

 

[Peter G. ShawParticipant @peterg-shaw75338]

David,

 

You are quite correct about random scrap material having struggled, and failed, with all sorts of rubbish. Perhaps I should have said “scrap material of a known provenance, eg EN1A”, after all, I imagine most of us do have bits left over from odd projects.

 

In respect of eyesight, I too am now struggling, eg, many years ago it was “that leaf on the tree 5 miles away”. Now it’s “what tree!”. I exaggerate, of course, but I do find nowadays that I am having to more and more use a pair of clip-on magnifying lenses, even for more mundane tasks as happened yesterday when I was repairing the bathroom pull switch. However, what happened to me was that the first indication of measuring problems was when I found that out of five 6in/150mm rules, the one by Rabone Chesterman was noticeably out on it’s millimeter scale compared to the other four. Needless to say, that rule is no longer used. Later, I was having difficulty measuring a diameter with a digital caliper, a mechanical difficulty in that I could not, for some reason, keep it at 90° to the work, so I changed to the micrometer for its wider tips only to find that the micrometer gave a sufficiently different reading to make me query what I was doing. Ultimately, I found that all my instruments had errors and that none of them matched. Given that the two digital units had a given tolerance of + or – 1 digit which implies that say 6mm could be anything from 5.99 to 6.01 mm, plus the measuring accuracy on top of that, then I’m afraid I rather lost faith in them. I now use a 0-25mm and a 25-50mm micrometer both with resolutions of 0.01mm plus a cheapo slide vernier with a resolution of 0.05mm, and a Starrett dial caliper with a resolution of 0.01mm. All these devices have been checked with Mitutoyo Micrometer Standard test pieces of 25, 50 and 75mm: said test pieces having a level of accuracy at least one order better than the 0.01mm resolutions. At least I now know that my devices are all measuring approximately the same and with the same level of resolution and, I hope, accuracy. Furthermore, I can, if necessary, split the divisions on the micrometers – bit difficult on the dial caliper, and impossible on the slide vernier caliper.

 

I accept that some people get good results with carbide. I never have, but then I have never bought the expensive stuff, and am rather loth to do so in case it isn’t any better. In any event, I rather like the idea of using carbon steel and making my own tools, and learning how to grind them, but that’s me. I do have an expensive milling cutter which I don’t think I’ve used yet, in part because the milling nachine is in the process of being brought up to a better standard and so is currently out of action.

 

GHT books. Yes there are some good ideas in these books, but, at the price they are, I do not think that they are justifiable especially after all the modifications necessary to suit my equipment. Even through the library system the GHT book cost me £8 for the loan – it certainly is not worth the £20+ sale price – I’d rather put my money into the Workhop Practice series books.

 

Regards,

 

Peter G. Shaw

[David LittlewoodParticipant @davidlittlewood51847]

Peter,

 

Your experiences with measuring devices prompted me to go and do a few quick tests with mine. Here are the results of measuring a 1.0000″ gauge block:

 

Mitutoyo digital caliper (2 examples) 0.9995″/25.39 mm

Cheap unbranded digital caliper 0.9995″/25.40 mm

Kanon vernier caliper 1.000″

M&W inch micrometer 0.9999-1.0001″

M&W metric micrometer 25.396 mm

 

Bearing in mind I took no special precautions on this test, I thought the results were quite creditable – every reading was within +/- one least significant digit of the 1″ figure. The cheap digital was impressive in accuracy, but fairly nasty to use, and is kept as a spare. To be able to read the vernier caliper I had to stand under a light and use a magnifying glass, which is a pain for normal use; after all, the whole point of a caliper is ease of use, and I shan’t be going back to using it anytime soon. The M&W inch micrometer gave a tenth either way depending on how many clicks I gave to the ratchet, which tells you something about how critical this is.

 

Like you, I need vision aids; I have a pair of reading glasses in my pocket, a stronger pair handy for close up work, and a magnifying loupe or ruper at each workplace.

 

Some people say that carbide tools cannot achieve cuts as fine as HSS; I have done some tests, and found it easy to take off half a thou and get an excellent finish. Taking cuts of a couple of tenths worked, but the finish was patchy and inconsistent. You should try a few quality tips and see how they work for you.

 

We’ll have to agree to disagree about GHT; for me, there’s more to be gained from his two books than in all the rest I have added together. Over half the items described are not machine specific, and even the ones that are specific to Myfords are described in a most informative way, with valuable asides on things like lathe adjustment, deep drilling etc. The Workshop Practice series is patchy; the Tubal Cain ones are uniformly excellent and I wouldn’t be without them (the tapping drill story in Drills, Taps and Dies is worth the cost alone). The rest are worth the price if you find the topic of interest, but it’s a good thing the price is low.

 

David

[Peter G. ShawParticipant @peterg-shaw75338]

Robin,

 

The Rabone rule does not have a ground off section. As it happens, the imperial side appears to be correct: it is just the metric side that is out.

 

On a purely personal note, I had come across this sort of problem with digital instruments during the 1970’s when doing some circuit design, and even then I reverted to analogue as being easier to use and sufficiently accurate for our purposes. What annoys me is that I didn’t twig that similar things would happen in a totally different environment. But that’s me – I don’t see things until they are thrust in my face!

 

David,

 

Your equipment is better than mine, although I now have a Starrett dial caliper and a Starrett 25-50mm micrometer. The two digital calipers are by Rolson (by far the best) and Workzone (from Aldi). The 0-25mm micrometer is by Feinmesszeugfabrik from the GDR, whilst the vernier caliper simply says “”Inox” on it.

 

Noting that you have two Mitutoyo digital calipers reminds me of another disadvantage of my digital calipers, ie the battery life – charitable described as poor. However, I did find a website in which the author was also experiencing poor battery life. He did some tests and discovered that the ON/OFF button simply blanked the display leaving the rest of the instrument working and thus drawing power from the battery. One thing that did come out of these tests was that the Mitutoyo brand was considerably better than the others in this respect.

 

Using the micrometers, I have adopted the one click idea of measurement. If I overshoot, quite easy on the 25-50mm micrometer, I then slacken off and try again. The idea being to always use the same amount of pressure each and every time.

 

Quite agree we will have to agree to disagree over GHT. I also agree that some of the WSP books are not worth the paper they are printed on and have in fact complained in writing about two of them, not that it got anywhere, but at least they know how I feel about those two. And yes, my Tubal Cain books are well thumbed, and in case, falling apart.

 

Regards,

 

Peter G. Shaw

 

[David LittlewoodParticipant @davidlittlewood51847]

Peter,

 

The Mitutoyo calipers are definitely my favourites* – but they are the old style. These have the “Off” and “On/Reset” buttons on the bottom edge, where they come easily under the thumb. The latest pattern, and virtually all other digital calipers I have seen, have the buttons on the front face, where you need to shift the thing in your hand to press them. Why on earth manufacturers adopted this pattern is an utter mystery to me. (I even, in my efforts to get a second Mitutoyo of the preferred pattern, bought one at full price from MSC, on the basis of the catalogue picture, only to have to send it back when it turned out to be the later unwanted one. Got one later on eBay.)

 

Sorry for the rant, but sometimes I wonder if manufacturers ever take steps to carry out any research into what people want!

 

David

 

*And yes, the batteries on them do seem to last almost indefinitely, unlike those on the cheap one.

Edited By David Littlewood on 02/11/2011 15:30:14

[John Stevenson 1Participant @johnstevenson1]

Welcome to the real world where everything is made of rubber !

 

I’m doing some parts at the moment, can’t say what they are because I’d have to kill you <g> ! but everyone has to go away, stand overnight in a temperature controlled room and be measured on a a CMM machine.

 

NONE of the results match the sizes they should be even though they are all done on the same machine in batches.

They are within tolerance but when you have made 7 identical parts with drilled holes placed in using a nearly new professional DRO system and none ARE identical then it makes you wonder.

 

The unanswered question is unless you have a series of parts measured how do you know there are errors? Easy on diameters etc with decent micrometers that are checked but are those flange holes you drilled on your rotary table exactly at 60 degree spacing ?

 

What’s even more upsetting is having to pay out to be told you are wrong and CMM’s aren’t cheap

 

John S.

[Peter G. ShawParticipant @peterg-shaw75338]

Quite true John, but if you are like me, which I know you are not, strictly an amateur with only a sketchy knowledge of the rubbery characteristicks of nominally solid & stiff materials, then you learn the hard way. And in my case it is the fact that not all measuring devices are equal, and that there is no such thing as exactitude, simply the best possible for the circumstances.

 

The only thing I can say now, is to quote L.C. Mason “In any pursuit it is generally a healthy sign when one begins to become critical of one’s results.” Which in my case translates into improving my measuring accuracy by discarding those instruments which do not match up, but as always, taking costs into account, and what I am trying to achieve. Now I could spend a lot of money on Mitutoyo digital calipers, but this is a hobby for heaven’s sake, so by eliminating the grosser inaccuracies and knowing the rest, I hope that I can produce work of a satisfactory standard without spending inordinate amounts on Mitutoyo stuff.

 

Funnily enough, I was reading one of Tubal Cain’s books yesterday in which he says that he uses tighter tolerances for a single hole than he does for a multi-hole cover where the cover may have to be waggled (my words) over the studs to get it on. It’s horses for courses, isn’t it.

Regards,

 

Peter G. Shaw

[Sub MandrelParticipant @submandrel]

“In any pursuit it is generally a healthy sign when one begins to become critical of one’s results.”

 

Combine with “good is good enough” and you have a healthy attitude to any hobby.

 

 

It’s like that with so many things. As along-in-the-tooth botanist I can vouch that the reliability of someone’s records is generally in inverse proportion to how much confidence they have that they are all correct. The best botanist I know showed me a plant last week. He said “I think this might be…”

 

Tubal Cain was probably the champion of coarse engineering. He could work to gold medal standards, but would only ever do a job as good as it needed to be, relied on sound engineering principles rather than guesswork (viz. what he said about locknut theory and low percentage thread engagement) and didn’t frown on hand fitting – he made a stuart steam engine entirely by hand to prove it could be done.

 

Neil

[Author]

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