Here is a list of all the postings Steve Crow has made in our forums. Click on a thread name to jump to the thread.
|Thread: Short drill or Spot / Centre drill first|
Chris, Is your rotary table the Sherline CNC model?
For jobs like this, I use stub length split point drills from cncpoorboy. They are very good quality. Being stub length, they don't flex much and eliminate the need for spotting.
25mm is quite deep for a 3mm drill. Do you need to go all the way through or will a blind hole do?
|Thread: What to look out for on shank size when buying|
Hi Chris, I'm a bit late to this thread.
I use Sherline 6mm and 10mm end mill holders all the time.
Like you, I initially got some cheap cutters that had an undersized shank, a sloppy fit with lots of run-out.
Now I get all my end mills from the "CNCpoorboy" ebay shop. Select their HSS Cutters and put them in price order, low to high.
You will see a whole range of plain flatted shank end mills of all sizes and flute count. I get the 3 flute type and use them on silver steel, mild steel and brass with success.
They are generally British made, Osbourn or Clarkson and they fit in the holders with a nice satisfying push fit. I have yet to break one.
Under 6mm are less than a fiver with postage and always very quick delivery. They are also good for quality 4 facet stub drills and carbide cutters. I've got a few reamer from them as well.
I have no affiliation with the company but I've used them for about 3 years now and everything I've got has been top quality.
|Thread: Cutting brass with saw questions|
Chris, I've been watching this thread with interest. I too have a Sherline lathe and mill and we have similar interests.
But please, do appreciate that people on this forum have taken their valuable time to give you good advice based on years of experience.
I have not seen anyone call you or your ideas "silly". Only polite encouragement and opinions. If those opinions differ from yours, don't take it as a criticism or an insult.
I hope you continue to post as I've learnt a fair bit from some of the replies - as I said, we have similar equipment and interests.
Please try to be less sensitive and take on board the massive reserve of knowledge this forum represents.
Like yourself, I've not been in this game for too long but I've learnt a huge amount from delving into this forum.
Back to the original subject. George Daniels "Watchmaking" has very informative descriptions and diagrams for crossing out wheels. He shows which files to use and in which order to get crisp corners etc.
Anyway, best of luck with whatever method you choose and keep us informed.
|Thread: Material for engine block.|
Thanks, all interesting stuff! I didn't know about the Rolls Royce connection.
I'm trying to find any scraps of plans and drawings on the web to help me with this. Do you know of any sources?
Thank you for your kind offer but I will pass on it. It's a bit big for my requirements and machinery.
I won't be attempting the quill drive and I don't even know what a "bomb" is! Maybe you can educate me.
In fact, the gear train isn't strictly scale, more "inspired by". My model will be running on compressed air and will be two stroke so there is no reduction between shaft and cam. Here's a drawing.
As you can see, this is a simplified version designed to resemble the original. This is with mod 0.5 gears, if I can cut mods 0.33 or 0.25 gears it would be more realistic.
It is good to hear from somebody who has worked on such an iconic engine and it's derivatives. I have never even seen one in the flesh.
Thanks Roger, I shall have a look at that.
Jason, due to my method for holding the piece, I can only drill from one end.
I would prefer for both parts to be the same material, I'm just sounding out ideas.
It's a 1/12 Cosworth DFV V8, 7.2mm bore, 5mm stroke.
I'll be boring and drilling on a Sherline lathe and the hole is 12mm dia and 50mm long so I think I'll struggle to hold a big enough end mill in the tailstock.
If I can find the headroom on the mill I see that Arceuro do a 10mm 45mm long end mill that I could get away with.
The joint is for assembly so I can get the con rods on the crank.
Another potential problem is I will be drilling/boring out the crankcase and sump out of 2 pieces bolted together. This picture should give you an idea of what I mean...
The green line is the outline of the 1" square bar and the sump will be made from 3/4 x 3/8 (or 20mm x 10mm) bar stock.
If I were to make the two pieces of different materials, would I run into problems drilling and boring? I should imagine a drill would want to wander into the softer of the two?
If anyone has experience of a situation like this, please let me know.
I want to make a model engine block from 1" square bar stock.
I've made a couple in the past from bright drawn EN3 but I would like to make this one out of aluminium, like the original. The cylinders will have liners.
My problem is I've never got on with aluminium. I get an unpredictable finish and it sticks to tools. Also I have many M1.6 and 12BA holes to tap and I'm not sure that the threads would cope with a lot of assembly/dismantling.
My only experience has been with 6082 and I realise that other grades are available (2011 sounds good) but I don't fancy my chances of getting my hands on a small length of square stock.
Which brings me to cast iron bar. I've not machined cast iron since the first year of my apprenticeship 40 years ago. Would it be suitable for a job like this? I believe it can be quite messy and I've got a kitchen table workshop so it might not be ideal.
Any ideas or suggestions welcome.
|Thread: New member from Bath|
I am a very happy Sherline user. The system is so versatile. For about £2,500 you can get a lathe and mill with a huge amount of accessories including a CNC rotary table like Clickspring uses for indexing.
I've just got the horizontal conversion kit for the mill. This enables you to turn the milling column 90 degrees in 3 different positions. This should give the potential to make wheels of much bigger sizes than anything a Cowells is capable of.
Everything I have got from Sherline has been well designed, well made and well finished. The documentation is superb as well.
Also, the service from Kevin of Millhill supplies (the UK importer) has been excellent. I have no connection with any of these, just a satisfied customer.
|Thread: Cutting small gears.|
That's nice! Does the dial work an eccentric cam for adjustment?
Would love to see plans for this.
I know, look at this beautiful tiny thing. Just don't look at the price.
And this would fit my Sherline milling machine and triple its value!
I can feel a project coming on....
Edited By Steve Crow on 01/05/2020 17:29:03
That is interesting, There is quite a wide variety of small size solid carbide end mills available, although a bit more expensive.
How many flutes would you recommend for HSS? It looks like 3 in the photo. And cutting speeds? Doesn't carbide like a high speed. But with HSS?
Any hints or tips welcome.
I used quite a simple drawing program, not CAD, and drew them exactly as I would have on paper using ruler, compass and protractor etc.
Hi Martin, yes, i took that into consideration but in most cases metric was close enough.
The exception is the 10-11 tooth. The alternative for this is 4.8mm so I can get use 3/32 for Mod 0.5 and 1/16 for Mod 0.33.
Also, I already have a good number of endmills in smaller metric sizes.
The trouble with milling single point cutters is you need the right size end mill for the correct radius on the tool.
The button diameters in Ivan Law's tables are all integers or halves for Mod 1 but are not all easily divisible for smaller mods.
I decided to draw up alternative dimensions for each tooth count. Using the alternatives, I can now cut Mods 0.25, 0.33 and 0.5 all using easily available end mill sizes.
This is what I came up with.
Can anyone see any flaws with this plan? Has anyone milled small single point gear cutters before? Any comments or question welcomed.
|Thread: Telescopic bore gauges.|
I only needed the 2 smallest sizes so I got a couple of Mitutyo rather than a set.
Lovely and smooth with loads of "feel", so much better than a no-name brand I have. Consistent readings too.
Using a micrometer stand makes all the difference as well (unless you've got 3 arms).
|Thread: Cutting small gears.|
I'm reposting the image as it was hard to see.
I want to cut gears in Mod 0.25 or 0.333.
As I need to keep the tooth count low I want to use 30 degree PA.
Originally I was going to use the "hob forming" method. I posted about it a few weeks ago and a few of you responded having used it successfully. Others were dubious.
I've done some drawing to find out what tooth profiles I'd get with a single pass and 2 passes with the work rotated 1/2 a tooth and the cutter moved by 1/2 a pitch. I then compared it to a tooth generated using Ivan Law's info. Here are the results.....
As you can see, the single pass will only work with extra depthing and it's got a crude profile. A second pass improve things a lot but still looks tight. I'm sure a couple more passes would help a lot but the accuracy of the tool movement would have to be very good.
For my application the distance between centres is fixed so I'm going to have a go at making single point cutters milled from carbon steel using Ivan Law's button dimensions. It seems to be a popular method for making horological cutter in the USA.
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