Here is a list of all the postings Mark B has made in our forums. Click on a thread name to jump to the thread.
|Thread: Grinding machine identification|
I made an impulse purchase today of a machine which looks like a very useful addition to my workshop. It's a little home made, but I suspect is based on a commercial machine.
I've posted some photographs of it in the hope that someone can identify it.
Edited By Mark B on 20/11/2021 21:06:27
|Thread: Ball screws|
I think I'm going to try the ball screw option which will be a SFU1204. In terms of mounting these, is there any preference to thrust bearings?
Understood; I'll avoid links to eBay items. Thanks Mark
My original post had a link to the ball screw kit from eBay, but this was removed... Is this not allowed in the forum?
Probably worth me saying a little more about what I'm doing. I'm basically trying to replicate a rose engine for decorative dial engraving.
This is the machine so far:
I'm going to attach 2 stepper motors, one for rotating the dividing head (in one direction only so backlash is not an issue), and another stepper for the left to right movement of the table which the dividing head sits on.
The idea is that you mount a dial on the dividing head which rotates as you apply an engraving tool to the surface. At the same time you move the head in a sine-wave type of pattern so add an interesting geometric shape to the dial. The sine-wave pattern could be quite small with an amplitude going down to 1 or 2mm potentially.
I've got the stepper motor for rotating the dividing head sorted although this isn't shown on the photograph.
The ball screw application is for the left to right movement of the table which the diving head sits on. This is the bit which makes the sine-wave or any other pattern I choose to make. The prototype I've made so far uses an acme thread, but the backlash is totally unacceptable for this application.
I'm planning on making my fist steps to converting a small machine to CNC and wanted some guidance on purchasing ball screws.
Eliminating backlash is a of particular importance to me as I'm planning on making small clock parts. I'm not sure that my budget will stretch to ground ball screws, so the cheaper rolled ones will be my starting point.
Lots available on ebay such as these and I wondered if anyone had any opinions on these? The kit includes the mounts which would be a good starting point potentially.
I've chosen 16mm screws here, but for a small machine (like an SX2 Mini mill for example), would 12mm be adequate?
Edited By JasonB on 13/10/2021 15:41:23
|Thread: Gas strut for Axminster SX2|
Thanks for the replies. I was on the verge of replacing the strut but wanted to check first this correct. I was expecting the strut to lift like a spring quill. A replacement wouldn't have made any difference, so I'll focus my efforts elsewhere...
I've just purchased a second hand Axminster SX2 milling machine which I've just started to set up. One possible issue I've found is with the gas strut. I think it might be worn out as whilst it holds the head in its current position, it makes no attempt to raise it.
Can anyone confirm if the strut is supposed to lift the milling head, or it is only for holding in the current position?
I've confirmed that the head moves freely and having removed the strut, I've performed a crude experiment with my bathroom scales which shows the downwards weight of the milling head is about equal to the lifting strength of the strut.
|Thread: Making Minnie water gauge|
Thanks for the replies. I've had another go and have managed to drill through a length of bronze. I think the comments from Jason about heat and Phil about slowing it down and hence generating less heat helped. I'd certainly noticed the bits getting hot on my failed attempts which resulted in grabbing / binding and breakage!
The bottom line is PB102 is horrible stuff to drill. I've managed it by slowing the lathe down to about 30rpm and super slowly advancing a drill bit in a small about, then enlarging it a couple of steps up. All with cutting fluid. It's taken ages to do but you just cant rush this stuff it would appear.
I've had to walk away from my workshop having had 2 complete failures at making my water gauge fittings.
My problem is drilling the length of a round section of PB102 bronze. My drill bits suddenly grab and snap off leaving am impossible to remove bit of drill bit in my nicely machined part!
I'm being super careful in advancing my drill bits. I've even been modifying my drill bits to zero the rake angle which is a trick I use for working with brass which has the same issue, but this hasn't helped.
Is there a reliable technique for drilling bronze over a long length without ending up with a broken drill bit stuck in the middle of your work?
|Thread: Amadeal end mill sharpener|
Thanks all for taking the time to reply to this. I now have a much better understanding of the Amadeal offering (which I'm not looking at any more) and the alternatives.
I feels like a Clarkson would be a very good solution with the right tooling, but this is a big machine which would take up a significant footprint in my workshop. I've seen one for sale which looks useful, but quite expensive.
I've also been looking at smaller options such as the Alexander. I can see one for sale here which is easier to store and a lot cheaper. Are these viable? They certainly look very useful of many other sharpening tasks.
I also see that there are Chinese clones of these machines available too, but I'm unsure of the quality of these.
Sharpening end mills is something I've never got around to equipping myself with. The machines out there look fantastic, but the cost of them compared to the price of the small number of end mills I use doesn't justify the outlay. There is one from Arc Euro Trade which looks like a luna lander but at over £700 that equates to a lot of end mills!
I did stumble on this the other day which looks interesting from Amadeal.
Has anyone got experience of this and how it is used? I've tried to research it but not found any reviews of youtube videos.
|Thread: 1" Minnie boiler stays|
Yes BP102 - typo in my post! It is what I used and it cuts okay with sharp HSS tools.
|Thread: Making end / slot drills|
I'm in the process of making a 1" Minnie traction engine and there are a few keyways included in the design.
I've got the keyway cutting worked out for my gears as per Mason's book.
The next thing I need to do it cut the slots on the shafts and I don't have a 3/32" milling cutter. Mason's book explains "Making small end cutting slot drills bas been described so many times that it should be unnecessary to detail the procedure here".
Can anyone point me at the design and technique for making a 3/32" slot / end mill?
|Thread: 1" Minnie boiler stays|
I just wanted to update on this. The cyclone burner I purchased was a huge success and enabled me to apply good heat to the inside of the firebox. This in turn has allowed me to deviate from Mason's soft soldering approach to boiler stays to silver soldered ones. My boiler inspector was fine with this alteration as it was a clear improvement.
The end result is that last week my boiler passed its initial pressure test of twice working pressure. It held 100psi for several minutes without any drop in pressure. Very pleased with that result so I can not proceed with rest of the project.
Thanks for all points on this!
I've gone down the route of getting a cycle burner as suggested and it makes a massive difference. With the burner going out all the time I've never have been able to use soft solder even.
Now I can heat inside the firebox and having chatted to by boiler inspector (who has since discovered my post) I'm going to silver solder plain stays. These will mostly be 5/32" copper rivets. For the hornplates mounting stays I'll use 4 x 3/8" PB120 stays on each side which can be drilled through for the mountings.
For the bronze bushes I've been using material which came with the boiler kit of materials. I'm not sure what bronze it is, but it works for silver soldering. For my alternative horn plate mounting stays, is PB120 okay like this: pb120 okay?
I have become aware of this post from a few years ago which ended up in a scrap lump of copper and silver solder at about the same stage I am at now: PGK's 1" Minnie
Its a remarkably similar story of someone following the book in the same way as I have so far. I'm a little concerned I'm following the same route at this point.
At this point I'm at the stage of having a low pressure vessel which passes the 10psi test looking for bubbles under water. The foundation ring did take a couple of cookings up with additional copper "fillings" in the hard to fill triangles around joints of the fire box.
The next stage is to add boiler stays and I'm a little concerned that the order I'm following in the book isn't a good one. I agree that silver soldering everywhere is the way to go, but I've got difficulties applying head inside the firebox. If I stick my Sievert 2941 7.7Kw burner inside the firebox it lacks air and goes out!
What if I get a bigger burner such as the Sievert 2942 26Kw. Would that allow me to melt the silver solder on the inside purely from heating from the outside?
I have tried an experiment where I use a heat gun blowing air into the firebox whilst trying to use my torch, but this isn't really helping the breathing issue...
This is my story so far: progress
Edited By Mark B on 13/09/2020 19:52:22
In answer to the first question (am I determined to use this old fashioned method?), I'd say I'm just after the best solution. My reason for considering soft soldering is because this is the method described in the book which must have worked for quite a lot of builders...
I do agree that silver soldering would be a better approach as everything else so far is silver soldered. I am also aware that cooking this thing up now it is almost complete takes a lot of heating to melt the silver solder. The final back-plate and foundation ring required a lot of heating.
Silver soldering anything to the outside of the boiler around the firebox I don't think is going to be an issue. I do worry about being able to do much inside the firebox. I tried an experiment this afternoon with my torch to see how it works when pointed inside the firebox... poorly I think is the best description. Breathing as described by Clive is very much an issue.
Although I have my throat plate and backhead stays made up I'm going to consult my boiler inspector for guidance.
Continuing with my Minnie traction engine boiler, I am now at the stage where I have complete boiler with passes the initial 10psi air under water test.
The next stage is to make up the bronze boiler stays which go around the firebox. They are threaded through the boiler front back and sides into the firebox and the book describes the process as soldering / sweating them into position. My question is what is the best solder flux for this process?
I have 60/40 tin/lead solder and bakers fluid but also have lead free plumbers solder and paste for copper pipes.
|Thread: Minnie blowdown bush|
Thanks for the pictures - this help a lot.
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