MadModder
Gallery, Projects and General => Project Logs => Topic started by: NormanV on August 09, 2014, 12:07:33 PM
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Having completed my milling machine I felt that the next thing to make was a milling vice. Like the milling machine I'll be using aluminium castings. This is a simple project, it only requires two castings.
This is the dreadful sketch that I made as preparation for the build.
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Some of the best design's started on a napkin!
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The patterns are very simple, but when I first tried to mould the sand for the moving jaw the sand in the recess broke away. To solve the problem I drilled a hole through the top of the pattern so that I could poke through the pattern onto a piece of cardboard that would help to release the pattern.
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Of course when I tried again it released perfectly!
Here is the casting for the moving jaw. I was eager to get it cast today as the weather forecast for the next few days is not good as we will be receiving the remains of an "American" hurricane passing over UK.
A chunk of sand fell out but it does not matter as all surfaces will be machined.
I will be able to machine it whilst waiting for the weather to improve so that I can cast the body of the vice.
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Norman,
Do you want any more sodium silicate? I came across another drum of it during a clear up the other day.
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Your casting skills are becoming legendary Norman! Nice work. :thumbup:
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Thank you Arbalist, but if you look at the surface finish that Steve (vtsteam) gets on his castings you can see that I have a long way to go.
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Hi Andrew, that is kind of you to offer me some more. Yes, I would like some, it worked very well with the cores that I made. In fact I still have one sitting on the shelf in perfect condition, I thought that it might degrade over time.
Thank you.
Norman
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I'll see what I can find by way of a bottle
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The square lug design looks the same as my Far East milling vice and seems to work fine.
My old Abwood vice was dovetailed though which is perhaps better?
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I'm sure that the square slide will be ok, I just have to make sure that there is no play to allow the moving jaw to lift. I suspect that a little play sideways will not be a problem, in fact it should allow the jaws to grip parallel if my machining is not perfect.
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I've started machining the casting. Mounting it was the first problem as not having a vice already meant that I needed to find another way to do it. I drilled and tapped the holes that will eventually be used to fix the clamps that fit on the slide. I used these holes to mount the casting onto two flat bars 40 x 6mm and then was able to bolt the bars down to the table.
I've partly machined the bottom of the casting and the milling machine is working nicely, it is quiet and rigid and giving a good finish.
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Whooo! I just had a bit of excitement. I am about to cast the main body of the vice. I'd lit the furnace with it's load of aluminium and gone into the workshop to tidy up when I noticed that the roar of the furnace had stopped. It is quite breezy today so I guessed that the wind had blown it out. I went to go outside to turn off the gas and purge it before relighting it when there was a load bang and it relit itself. I'm glad that I wasn't standing over it! There was no harm done and it now has a wind shield around it.
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Well that was a disappointment, the moulding of the sand went well, likewise the pour. When I opened the mould I got quite a shock. The surface finish of the casting was amongst the best I have had, nice and smooth and no corners broken away. I had gated it from the ends so as to avoid too much hacksawing, I expected some shrinkage on the tops of the end blocks and allowed extra material to cover it. But, when I turned it over I was greeted by a large amount of shrinkage and the metal had torn apart on the inside corners!
Well it's back in the pot tomorrow, weather permitting, and I'll gate it from the tops of the blocks, I might try to extend the gates in order to get a larger head of metal to reduce shrinkage.
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Norman,
I would have poured that shape in the vertical, gating from the bottom and left a thickness for machining off the top. I know it means a custom cope & drag :wave:
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Forgive my opinion here, too Norman, and take with a grain of salt.... I like the horizontal layout okay, and the bed is important to preserve clean compared to the ends -- keeping that part low in the mold helps.
I think gating the sprue high up will wash sand down the ends during the pour, so I like the low gating as well.
You just basically need to feed metal into the inside corners during solidification so I'd try a bigger riser off the edge at that corner, and thicker than the upright is --maybe even a blind riser -- like a ball of styrofoam. The riser has to solidify last, so needs to be thick.
Sharp Inside corners in massive casts tend to tear like that since they solidify last, and the leg and main base tend to pull metal away from it while soft.
It helps if there's a radiuus there instead of a sharp corner, even if you machine it off afterwards.
Also a bevel on the outside corner can help.
Also the present sprue and riser look small. They should normally be larger in cross section than the largest thickness you are feeding -- which looks like the bottom of the uprights. That way they hopefully won't solidify before the corner does and can keep feeding iliquid metal.
I know just a bunch of suggestions, but some or one of them might help.
Your base does look good!
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Thank you Andrew and Steve for your suggestions. I think that I will keep it horizontal for the next try. I'll add fillets to the corners and make the header and riser bigger. Funnily enough I did not have any problems like this with the much larger castings for the milling machine and I used the same size header and riser for those as I have here. I am sure that the gates between these and the body of the casting are too small as I was trying to keep the metal section small so as to reduce the hacksawing needed, my angle grinder is bust!
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I kept a pile of baked bean tins with both ends removed in my foundry. Ram them up tight with floor sand, then press a piece of 1.5" copper pipe through them, and hey-presto you have a taller riser. I used to sculpt them at the upper end to a funnel shape with one of my moulding tools, and place them on the cope over the existing pour and riser, putting a little sand round them to seat nicely.
It also had the side effect of producing useful bars of the alloy for either machining or testing
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I have already prepared some cans for tomorrow!
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Here is the reworked pattern. I've done it quite crudely but I am sure that it will be OK as I intend to machine it all over. I've put in quite large fillets where I had the splits and added a block at each end for the gates. I have made patterns for the header and riser to mould in situ. I normally cut them with a piece of steel tube about
1 1/4" diameter. I will also raise the height with two cans as suggested by Andrew.
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As I suspected, even though the pattern is a bit rough it moulded up OK. Here is the flask set ready for pouring. I am now waiting for the aluminium to melt.
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Good morning Norman!
I meant small radiused fillets -- just a wipe of body putty on the old pattern, and chamfering the outer corner to reduce mass at the joint.
The ends are pretty massive now, and even thicker at the base than the new thicker sprue and riser.
My guess is that the joint will continue to stay liquid internally longer than any other part of the pour.
You really hope the sprue and riser are the last to solidify so that they can feed everything else.
But maybe it will work. As Bohr said, prediction is difficult, especially about the future.
I hope for a good part! :thumbup:
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Oh! I totally misunderstood you. The internal corners were already filleted with body putty, there were no sharp corners. I couldn't chamfer the outside corners as that is quite an important part of the base. I'm going to knock it out in a few minutes and then we will know what the outcome is.
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It turned out fine. There is a little shrinkage at one end but that will be machined out. There are no cracks.
The header has suffered enormous shrinkage, right back down inside the tin can. The top of it can barely seen in the second photo.
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Nice to see this coming along, Casting is such a buzz!
Regards, Matthew
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Just curious, will aluminum hold up to the rigors work-holding on a milling machine?
Bill
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I hope so. That is why I have made the castings quite substantial and it will have steel facings to the jaws and the screw will run in a steel nut.
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Andrew's can did the trick!
I mean the riser.....
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Yes, the cans certainly took all the contraction.
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And they stayed hot because of the sand in them to insulate. I like it!
Your square sprue and risers look bigger in the last picture than I realized. Good work!
Your vise should be pretty tough with your big fillets --are you planning to mill the upper one off because of the top plate, but leave the lowers on the sides and just shape the moveable jaw base to match them?
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Funnily enough I found a box of topped and tailed bean cans stored with my foundry bits since my move 7 years ago - I'm surprised that I didn't chuck them !
Norman I've not forgotten the Sodium Silicate - first bottle I set ready the wife used as a puppy toy and is now in bits :bang: Waiting for large lemonade bottle to empty which shouldn't take long as more grandchildren coming at the week end - yikes run for the hills :bugeye:
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Steve, I have to remove the top fillet, I'm not sure about the bottom ones. I may have to remove them to make space for the mounting bolts. I was intending putting pins in the bottom to engage with the Tee slots to set the vice square to the mill.
Andrew, Thanks, I'm in no particular hurry.
Enjoy the grand kids!
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It would be nice if you could keep those side fillets at the fixed jaw end,
For a hold down at the fixed jaw end, my vise has a lug extending off the main casting, and two lugs on the side of the base casting.
If you wanted a lug at the fixed jaw end you could shape one out of the gate. To get more material you could cut that sprue off horizontally, flush with the top of the gate.
Here's a pic to explain the lugs:
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/TecumsehBuild/Vice9.jpg) (http://s786.photobucket.com/user/vtsr/media/vtsr/TecumsehBuild/Vice9.jpg.html)
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I have checked the casting against the milling machine table and find that I won't need to machine away the side fillets. This black dots on this photo show where the fixing bolts will go. I plan to have hollow dowels on two of them to locate the vice.
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You're doing great so far, looking forward to seeing how this turns out Norman!
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I've machined the moving jaw all over, I just need to bore the hole for the adjusting screw to pass through. The box slide turned out nice and smooth with no play. I've temporarily attached the clamps with countersunk screws until I can obtain some shallow head cap screws.
The screw holes that come through the top will be filled. I had to drill them right through to enable me to clamp the piece on the mill.
Next job is to start machining the main casting.
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It's a bit like a MakerBot if you think about it, a machine making bits of itself :clap:
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Looking good, Norman! :thumbup:
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Nice work Norman. For what it's worth my vice has hex bolts (and washers) for the moving jaw slides.
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Hi Norman
Pleased your casting turned out well, I have been using the tin can risers for several years. I originally got the idea from Myfordboy's web site, and used thick walled pvc piping for some time. However one day I had a slight spillage, and set one on fire, so now use pineapple tins as they are wider than beans tins and allow a larger pouring and shrinkage reservoir.
The vice is coming on nicely.
Cheers David
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Thanks everybody. I got most of the machining on the main casting done this evening. I'll post some pictures tomorrow.
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As promised, here is the main casting with the slide attached. I had to use a mixture of screws as that is all I had, doesn't affect the performance but doesn't look too good.
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Here it is with the moving jaw installed, I had to machine some of the fillet away in the lower corners as it obstructed the moving jaw.
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I was anxious as to whether the care that I took to get the jaws parallel had paid off so I made a couple of wooden wedges to clamp it and was delighted to find that it clamps squarely.
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Can somebody tell me the diameter of the clamping screw usually used on a 4" milling vice. I am undecided whether to use 1/2" or 5/8".
Thanks.
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Norman my vice has a 5/8inch screw, and that is what I would use.
Cheers David
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The steel facings are now fixed to the jaws, they don't line up perfectly but that will be the first milling job on it when it is finished.
I've found two problems with the "make it up as you go along" method of design.
1) There was not enough space to fit a 5/8" clamping screw so I will have to use 1/2" but I don't think that will be a problem.
2) My choice to use shallow head cap screws to hold the clamps was unworkable as I did not make enough space for those screw heads and the clamping bolts to pass each other. I can't remember why I did not want to use countersunk screws for the clamps but that is what I have had to do.
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I've got the holes prepared for the clamping screw. I had originally planned to buy an acme threaded rod for this but have decided to use standard 12mm threaded rod, albeit left hand thread. Where it passes through the fixed end of the main casting I have made the hole oversize so as to avoid any problems with alignment.
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I've got the holes prepared for the clamping screw. I had originally planned to buy an acme threaded rod for this but have decided to use standard 12mm threaded rod, albeit left hand thread. Where it passes through the fixed end of the main casting I have made the hole oversize so as to avoid any problems with alignment.
Norman,
I have a few 9/16" ACME leadscrews (1/8" pitch) if you would prefer something a bit beefier than M12. I have a right handed one with a very snug fitting nut and a left hand one where the nut is a bit sloppy.
You would be welcome to either as they're just taking up shelf space. (They came out of my Alexander engraver which I converted to CNC using ballscrews.)
Cheers.
Phil.
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Phil, that is very kind of you. I would like to take the left hand one, I don't think that a bit of sloppiness on a vice is a problem. Certainly less of a problem than the mental gymnastics trying to remember to turn the vice handle the "wrong" way.
I'll send you a PM.
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Norman, your vise looks like it already wants some work to do! Phil great that you can help out! :nrocks: :clap:
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Norman
Very nice and the patients is just what is needed with home foundry's. The vice is starting to be very impressive, you have done a nice job on it all. The only thing to be cautious with would be cranking down when holding anything. The thinnest section will give first. Good looking project, good luck.
Nelson Collar
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Thank you for the kind comments, I think they were a little premature the casting has warped! I went to do some more work on it and found that it now rocks when placed on a flat surface. On inspection I found that I could fit a .5mm thick ruler under one corner when it is pressed down on the flat. In order to remove the slide and moving jaw I had 8 screws to remove, two of which were hidden under the moving jaw. Due to the distortion the moving jaw was tight to move, I pulled on it and it went suddenly, and bit me!
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I now have two choices, I could leave this casting for a while to settle and then remachine it or I could make another casting and also leave that to settle before I machine it. I think that I will make another casting anyway just in case the first one is not recoverable. Either way it will be some time before I can complete the vice.
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Ouch and ouch! Sorry about the problems, Norman. I'm sure you'll have the vise working. :beer:
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I didn't think aluminum would warp like that!
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Unlike cast iron, at least with aluminium you can apply judicious bending and it will take a slight bend without cracking - usually :scratch:
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I don't think I've ever had an aluminum casting warp after milling and I've got a lot on my lathe and accessories -- but I guess it can. Other than the lathe bed, and headstock, I haven't done as massive castings in general. The lathe has stayed straight, and I didn't age it before scraping.
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I have heard of iron castings warping and hadn't expected aluminium to be any different but went ahead with machining it anyway. My previous experience with the bed of a Gingery lathe did not result in any warping but that has better bracing than this casting. I could try bending this one to reduce the warp but I don't have the facilities to do it.
An idea has just come to mind, I will put it back in the furnace and heat it for 30 minutes, and then let it cool down in the unopened furnace. It normally takes an hour for this amount of aluminium to melt. so that should stress relieve it. It will be interesting to see if it makes a difference. At least the only cost will be the gas!
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Most aluminum's are notorious for warping during machining. During machining you set up a surface stress and it will warp. We fight that problem all the time where I work. Some of the aluminum types are horrible and warp with even the lightest machining cut.
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It's worth a try to stress relieve an al casting to be machined by baking it for 5 to 8 hours at 450-500 degrees
Dave
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I've cast it again and this time had a bit of an 'event'. As the header and riser filled to near the top the mould opened and metal started leaking out of the side. I rapidly put my foot on top and pressed down, that stopped the leak. I poured in the rest of the metal from the crucible and waited for the metal to have a chance to solidify before I removed my foot.
To my surprise I still got a good casting, there is quite a lot of contraction at the riser end but there is enough metal there to do the job.
I think that I might take Beone's advice and stress relieve the castings in the oven. Beone it might have been a good idea to specify the units when quoting a temperature. When I made my first furnace Dave Gingery suggested curing it at 400 degrees in the oven, I did not give it a thought and set the school workshop oven at 400 degrees and nearly burnt the school down 400 degrees Celsius is very hot!
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Oh! Yeah! That's Fahrenheit if I set my wife's oven for 500 Celsius I would burn the house down!
Dave
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I've stress relieved both castings in my domestic oven. I had planned to leave them in for 5 hours but fell asleep so they were in the oven for nine hours. I was a bit concerned about the cost of electricity but was pleased to find that it only used £3 worth.
I'll start machining the new one tomorrow.
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I've now got the second casting almost to the same stage as the first one but even this warped slightly. When I took it off the mill after milling the base yesterday it sat absolutely flat on a surface plate. By this morning it had developed a slight rock, it is not a major problem as it straightens out when I clamp it down.
You may notice from this photo that I have added mounting lugs to fit the tee slots on the milling table to enable me to mount it in either direction on the mill.
Tomorrow I will start working on the lead screw that Philf kindly sent me.
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Norman it looks much better with the mounting lugs.
Cheers David
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This vice is nearing completion. This morning I clamped a piece of round bar in it and was pleased to see that the jaws are parallel and it clamps evenly.
But, I did learn some useful lessons today also. I wouldn't class myself as inexperienced but most of my engineering work has been with steel, cast iron and aluminium. This morning I had to machine the bronze nut for the leadscrew on my lathe. After a couple of dig-ins using my usual tool I thought that I would grind a new one with no top rake, well, it's chalk and cheese! After that I backed off the point of a drill and it went through with no grabbing. I have always been too lazy to grind separate tools, all I can say is, "what an idiot I am!"
The second lesson was not to forget to lock the slides on the milling machine if I want to prevent the cutter from digging in.
All in all a couple of useful lessons, I knew about it but had just been in too much of a hurry.
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Sounds like you're coming along, Norman. Can't wait to see the finished vise at work! :thumbup: :beer:
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Taaraaah! It is complete!
I have just finished assembling it and am delighted at how smoothly it operates and firmly it clamps.
I fitted a roller thrust bearing on the screw which must help with the amount of force needed to clamp it.
The capacity of the vice is 100 x 75 x 25mm, I designed it to be 100 x 100 x 25 but the plain section on the screw prevents it from opening further. Next time I plan to make any equipment I should ensure that I have all the parts before casting any metal.
All in all it's been a great project and not too time consuming.
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Excellent stuff Norman - glad it's finished and working.
Now . . . what's the next project using the milling machine and vice :clap:
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Nice one Norman!
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Thank you Andrew and Arbalist.
Andrew, I'm thinking about a rotary table, I have a very nice 30:1 worm and wheel that could be suitable.
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Nice project, looking forward to the rotary table!
regards, Matthew.
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Nice one Norman.
I'll see if the other LH screw has a shorter unthreaded portion when I'm home on Saturday.
I find a dividing head more use than a rotary table.
Cheers
Phil
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Nice vice
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Looks great, Norman! :bow: :bow: :bow: :clap: :clap: :beer:
I bet you could make a tap and with that, a die to continue the thread on your existing screw so you could clamp full length. I used to do the same thing for shoulder bolts that I needed threaded full length. I'm assuming the screw isn't hardened....
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Hi Phil, that would be great but it is not a problem, the vice will still be very useful as it is.
Steve, yes, I suppose I could do what you suggest, the screw is not hardened. The piece that I cut off is about 4" long I could cut flutes in it and case harden it but I don't think that the reward would be worth the effort.
What is the difference between a rotary table and a dividing head? If I make division plates to fit the rotary table surely I will get the best of both worlds. With a 30:1 ratio I will get 12 degrees per turn of the handle, if I use a 3" dial 120 divisions would be spaced at approx. .08" giving me 1/10 degree spacing. I haven't done the maths for division plates but I would think that I could probably get most divisions that I might need.
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Hi Norman,
As long as you can mount the rotary table with its axis horizontal as well as vertical there's not a lot of difference. My dividing head is adjustable to anything in between but 99% of the time it's set horizontally.
Phil
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hi and a job well dun