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Juliet
Jul 26, 2020 10:59:26 GMT
Post by ettingtonliam on Jul 26, 2020 10:59:26 GMT
What speed are you using with those cutters? I found getting up around the 4000 rpm mark considerably reduced my breakage rate.
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smallbrother
Elder Statesman
Errors aplenty, progress slow, but progress nonetheless!
Posts: 2,269
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Juliet
Jul 26, 2020 11:19:51 GMT
Post by smallbrother on Jul 26, 2020 11:19:51 GMT
What speed are you using with those cutters? I found getting up around the 4000 rpm mark considerably reduced my breakage rate. No DRO on my mill but I turn it up towards the top end.
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stevep
Elder Statesman
Posts: 1,070
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Juliet
Jul 26, 2020 11:58:24 GMT
Post by stevep on Jul 26, 2020 11:58:24 GMT
Pete, if you are breaking cutters, then I think you have a problem.
I've got lots of blunt cutters, but no broken ones (I think). (That's tempting fate!)
You are either traversing the table too fast, or taking too big a cut (either on the side, or downwards). Or you could be cutting through all the swarf in the pocket and jamming everything up.
I think it was Roger who said you can use a cutter at any speed, you just need to adjust the feed rate to be appropriate. So maybe you should reduce the cutter speed, make sure the swarf is blown or brushed out, and reduce the feed rate.
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smallbrother
Elder Statesman
Errors aplenty, progress slow, but progress nonetheless!
Posts: 2,269
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Juliet
Jul 26, 2020 12:29:44 GMT
Post by smallbrother on Jul 26, 2020 12:29:44 GMT
Pete, if you are breaking cutters, then I think you have a problem. I've got lots of blunt cutters, but no broken ones (I think). (That's tempting fate!) You are either traversing the table too fast, or taking too big a cut (either on the side, or downwards). Or you could be cutting through all the swarf in the pocket and jamming everything up. I think it was Roger who said you can use a cutter at any speed, you just need to adjust the feed rate to be appropriate. So maybe you should reduce the cutter speed, make sure the swarf is blown or brushed out, and reduce the feed rate. As this is the first time of doing this operation I would imagine it is a combination of all those factors. Just before the second one broke I was withdrawing the cutter and blowing out the swarf but maybe not frequently enough. A number of things I can try and not so much to do now.
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stevep
Elder Statesman
Posts: 1,070
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Post by stevep on Jul 26, 2020 17:56:58 GMT
Pete, I wish you well in your next attempts. Take it slowly and gently, and I'm sure you will get here.
Cheers
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Juliet
Jul 26, 2020 21:16:35 GMT
Post by jon38r80 on Jul 26, 2020 21:16:35 GMT
I used to break small milling cutters with annoying frequency usualy just before I finished making a part. turned out it was pushing the travel too hard, its very tempting to push on when you have been standing for half an hour watching dials and chips flying about. I dont break the 2mm cutters anymore.
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smallbrother
Elder Statesman
Errors aplenty, progress slow, but progress nonetheless!
Posts: 2,269
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Post by smallbrother on Jul 26, 2020 21:56:13 GMT
I used to break small milling cutters with annoying frequency usualy just before I finished making a part. turned out it was pushing the travel too hard, its very tempting to push on when you have been standing for half an hour watching dials and chips flying about. I dont break the 2mm cutters anymore. I think you have hit the nail on the head. My eyes struggle to see what is happening even with my reading glasses and a magnifying glass. My back is playing up also and to stand there in a poor posture, poor visibility, delicate operation to perform, chances are something will go wrong. Anyway, all terrific experience, and as I've said many times, I appreciate the high quality work that others turn out all the more for having a bash myself, even if problems arise. I think it would not be a such a bloody good hobby if it all went swimmingly every time! Pete.
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smallbrother
Elder Statesman
Errors aplenty, progress slow, but progress nonetheless!
Posts: 2,269
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Post by smallbrother on Sept 18, 2020 16:56:50 GMT
I broke a drill bit off in a steam passage and have tried Alum to remove it without success. Did a bit more research today and it seems you need to simmer the mixture for a few hours. Here it is simmering on top of the cooker. A small screwdriver has gone a long way down the hole so it might be working. Pete.
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Juliet
Sept 19, 2020 8:26:43 GMT
via mobile
Post by osiris09 on Sept 19, 2020 8:26:43 GMT
It took me 4 days for some of my larger bolts. Just watch out for your tray as it's also steel so can be eaten. I use Stainless pots and a little heat plate and leave it running in the garage. It works well if you make the solution saturated.
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Post by philh1aa on Sept 19, 2020 9:10:45 GMT
I am in the process of milling my Rob Roy ports. It calls for a 3/32" slot for the inlet and outlet and a 1/4" wide slot for the exhaust. I am just going to use a line of carefully drilled holes for the 3/32" wide slots e.g., drill a series of holes at say 2mm diameter then carefully open them out to 2.4mm so that they all break through the sides and 'link' together.
The design calls for 3off holes from the ports to the ends of the cylinders so I can't believe my method for the ports will not work just fine.
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rrmrd66
Part of the e-furniture
Posts: 339
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Post by rrmrd66 on Sept 19, 2020 9:17:09 GMT
Hi Pete
Agree with osiris09
Use Pyrex dishes. Make sure solution is saturated (the point where no more Alum crystals will dissolve in warm water) Important to keep solution simmering (I used a camping stove) and topped up - complete immersion. Look for stream of small bubbles - means it's working. 6BA tap in Gunmetal will dissolve in approx 12 hours
Good luck
Malcolm
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Juliet
Sept 19, 2020 10:53:22 GMT
Post by ettingtonliam on Sept 19, 2020 10:53:22 GMT
I ordered 'Alum' from an internet supplier and got Potassium Sulphate, which doesn't work. It needs to be Potassium Aluminium Sulphate, so make sure you've got the right stuff.
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Juliet
Sept 19, 2020 11:00:18 GMT
Post by ettingtonliam on Sept 19, 2020 11:00:18 GMT
I am in the process of milling my Rob Roy ports. It calls for a 3/32" slot for the inlet and outlet and a 1/4" wide slot for the exhaust. I am just going to use a line of carefully drilled holes for the 3/32" wide slots e.g., drill a series of holes at say 2mm diameter then carefully open them out to 2.4mm so that they all break through the sides and 'link' together. The design calls for 3off holes from the ports to the ends of the cylinders so I can't believe my method for the ports will not work just fine. Well, yes, it will work, but you'd be better off, once you've drilled the 2mm holes, opening up the port with a 3/32" end mill, to give straight edges, so the valve opening will be more consistent. In my impecunious youth, I did what you are proposing, then straightened the edges with a tiny cold chisel ground out of a broken HSS drill, gthen finishing off with a warding file.
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Juliet
Sept 19, 2020 11:47:37 GMT
Post by philh1aa on Sept 19, 2020 11:47:37 GMT
I have used a Dremel with a diamond burr to remove some of the remnants but please forgive me for saying this. I don't accept for one moment that it will make even the slightest difference.
Phil H
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stevep
Elder Statesman
Posts: 1,070
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Juliet
Sept 19, 2020 14:50:14 GMT
Post by stevep on Sept 19, 2020 14:50:14 GMT
The reason for having straight edges to the ports (and valves) is so the valve opens suddenly to steam (or on the inside, exhaust).
If your ports are a series of scalloped edges, assuming your valve is straight sided, at the point of valve opening you will be exposing a very small area to admit the steam.
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Juliet
Sept 19, 2020 16:10:41 GMT
Post by philh1aa on Sept 19, 2020 16:10:41 GMT
Yeah I know, I still don't accept it will make a significant difference. Have you honestly tried it?
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stevep
Elder Statesman
Posts: 1,070
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Juliet
Sept 19, 2020 17:37:19 GMT
Post by stevep on Sept 19, 2020 17:37:19 GMT
I shall be interested to see how your engine goes with the ports like you describe. (Could you post a picture). Maybe we've all been worrying too much for many years?
I'm sure others will be interested too.
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Juliet
Sept 19, 2020 18:58:06 GMT
Post by philh1aa on Sept 19, 2020 18:58:06 GMT
Steve,
I wish I could post pictures but this particular laptop doesn't want to accept the systems that can host the pictures - I've tried a couple of times. I am able to post pictures on the ME site under Philh1 (I think it is). I will add some shots of the port faces over the next few days or so on that site and ask a similar question - and see what comes back.
Trust me, it will be a pleasure to have it finished and running even if its performance is bad because of poor porting. But I am genuinely curious now. Has anybody done the comparison or do people just worry about it? For example, are there any ME articles showing the pros and conns of port and passage arrangements? Another example is that the cylinder entrance seems to vary too. I see quite large arcs milled into the edge of the bores and very wide passages through to a couple of holes via a quickly filed edge close to the bore.
Phil H
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Juliet
Sept 19, 2020 19:06:04 GMT
Post by philh1aa on Sept 19, 2020 19:06:04 GMT
Steve, just to confirm, my name on the ME site is Phil H1 and I currently have a few pictures of where I am up to on Rob Roy.
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Post by suctionhose on Sept 20, 2020 7:19:33 GMT
Yeah I know, I still don't accept it will make a significant difference. Have you honestly tried it? I think we're clogging up Smallbrother's Juliet Thread here but briefly, yes, tried. In quest for improvement made slots. Every little bit helps and that's why some engines run and others run really well. For Rob Roy turning over at hundreds of RPM in full gear all the time, holes will be fine.
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