Thread: Riser Block for Mill out of Cast Iron Hollow Bar - where to get the Bar?

RC...i was very curious to see what was on their site so loaded up IE and it went to the site with out giving any warnings like firefox did, but a lot of data did come down.....HD was whizzing around doing stuff......so something was happening

i was either brave or stupid...only time will tell which one I guess...probably the later......anyway then up popped my virus scanner

I dont think the trojan is very dangerous... but one never knows

here is a screen dump

not to chuck a spanner in the works but why cant you just just use steel hollow bar/pipe and face it in the lathe???? it would be much easier and cheaper i know at work we have heaps of offcuts that would be a suitable size so i cant think why your local engineering shop wont be able to help you and even if they couldn't find you a bit in there racks you would be able to buy some from any heavy size steel supplier cut to size then as i said just turn it in the lathe and you wont need to grind it

Thanks RayG for the heads up about the possibility of making my own mould. If they do allow this - it opens up the possibilites of lots of other parts I have been thinking about. I will have to get a quote first - it might be more than I want to part with!

I have already come up against the problem of not enough space between the spindle and table when trying to machine some holes, and I know I have some larger parts in the machines future. I am yet to fit a 320mm rotary table to the mill - which increases the table height by 120mm - making the useable space even less. Just thinking about ways to accomplish more space/capacity for when I need it. H&F sell 150mm riser blocks for their BM family of mills for $572.

I am hoping that by having it ground on a surface grinder I will end up with better-than 5 micron finish with respect to parallelism of the top and bottom faces. The wall thickness of the column is less than 20mm from memory(could be wrong), so I was thinking that by maintaining this wall thickness, or greater, it shouldnt compromise the strength. By making it taller it is in effect a longer lever, which would allow slightly more deflection of the column under heavy loads - but I can live with that. Repeated passes at the same relative position of the table and tool should allow this deflection to level out when finishing.

Can you produce this level of parallelism in a lathe? I hadnt really given it much thought - what does everyone think?

If you search through here you may find some info

"http://www.practicalmachinist.com/vb/search.php?searchid=2708994"

I dont see how you could turn it that close. If it was a circle you might, but lathes are set up to face concave at about .0005" an inch(from memory I can't find my ref just now, but I'm sure someone will correct me if I am to far out).
Wouldnt milling me close enough? Although I dont think your mill would have enough Y axis

Hi Mark,
I have been watching to see what your ideas were for raising the head. I agree with you about lack of space and you would be worse off because of the NT40 spindle.
I bought a 300mm rotary table but found the bolt holes would not even go near fitting the table, and it took 2 blokes to lift it. I returned it and bought a 250mm one and it fit's nicely and though heavy can be lifted. I can always make up a plate to bolt to it for larger jobs if needed. I made one plate for it so far that will take my 160mm 3 jaw, or my 200mm 4jaw or the 250mm 4 jaw i bought for it.

I scratched my head for a long time thinking of a way to raise the head on one of these mills. The main thing was to be able to use the horizontal arbor still as well.

I started on mine about a month ago but have been laid up for a few weeks so I haven't progressed much.
You can see my design in the pictures below, it is all steel no castings. I was first going to raise it approx 160mm, which just meant placing the bottom bolts in collar that go into the ram up to the top. After dummying it up I found with a ER collet chuck in the spindle, it would be higher than the ram dove tails, so I decided to come back down and raise it only 100mm.
Your situation would be different because you have the NT40, from what I have seen it is around 60-70mm lower at the spindle. Because of that so you would be able to go the full 160mm.
I was going to use 32mm plate but after getting it and felling the weight I thought it was an over kill for the job, so I went with 25mm plate.I marked the plate up then drill the holes under size to fly cut it.
You can't see it in the photo's but I ended up placing 2 strips of 25mm square bar across the table with counter sunk allen head bolt's to hold it down to the table. I drilled 2 other holes in each so I could bolt the plate down. I then fly cut the 25mm square so to cancel out any errors from anything. Using coolant I fly cut one side of the plate flipped it over then did the other, and come out with no more than 0.005mm on each corner.
The wedge box on top is getting made with a 12mm base 10mm sides and 10 x 20 webbing welded in, and will be fly cut as well after welding. There is a cast in knob in the top of the ram which looks to be for a lifting lug. I will be tapping it M16 and making a claiming system at the end where the square opening is at the back, where the sheet metal is.
I plan on facing the front of the wedge box with the fly cutter in the horizontal spindle to get it to be true with the front of the ram. The wedge box will be attached to the 25mm plate with 5x10mm bolt's. Doing it this way I am only drilling 1 hole in the ram which is were the lifting lug should have been if it was a shorter geared any way.

The first picture shows the design I am using,
The second one is a design that would suit you if your spindle is like picture 4.
The third picture is my design for the wedge box.
The 4th picture is just to show Ray and others with this type of mill the NT40 spindle and how it extends down further giving less room.
The last is the cast piece for the lifting lug.
EDIT picture 5 is fly cutting the plate
Dave

Ps
If I don't post for a week you will know I used up all my 1 finger typing on this post,LOL

Originally Posted by Stustoys

I dont see how you could turn it that close. If it was a circle you might, but lathes are set up to face concave at about .0005" an inch(from memory I can't find my ref just now, but I'm sure someone will correct me if I am to far out).
Wouldnt milling me close enough? Although I dont think your mill would have enough Y axis

Hi,
I read this a few years ago and after checking mine near new lathe back then and recently when I moved it, it faces dead strait with no concave. I see some blokes on PM think it is a myth but others swear by it.
With a bit of mod you can get these mills out to 280mm maybe a little more in the Y axis. I have mine to 280mm but can't go any further because of the glass scale travel is at it's max.

Dave

Originally Posted by Dave J

Hi Mark,
I have been watching to see what your ideas were for raising the head. I agree with you about lack of space and you would be worse off because of the NT40 spindle.
L

Actually a NT40 spindle may give you more space depending on what tool holder you are using...

I know with certainty that an NT40 ER40 collet chuck sticks out less then an NT30 ER40 collet chuck as with the NT40 as the taper is a lot larger it fits the ER40 taper right up inside..

I understand what you mean RC but,
If you look at the picture of the mill head the 30 doesn't have the extra block on the bottom of the spindle, which is about 60-70mm high. So any advantage of the 40 would be lost because of it, and I think you would find it would still sit lower compared to the 30.

Dave

EDIT
This is a picture of my Taiwanese NT30 ER32 collet chuck

Thanks to .RC. for his Practical Machinist suggestion. Found some info there.

Thanks to Dave J for sharing his plans. It wasnt a solution I had considered. I do have some questions(lots) though Dave. Photo 4 is an accurate depiction of my quill/spindle setup. With the table at full height, I only have 15mm between the spindle and table.

I will be tapping it M16 and making a claiming system at the end where the square opening is at the back, where the sheet metal is.

1. Can you explain the above a bit more please? What is a claiming system?
2. Where the base of the wedge box touches the top of the ram - you said you will be facing this part of the box - but how will you prepare the top surface of the ram?
3. The 25mm bar that you bolted under the plate when you faced it - essentially they were parallels that you could fix to - correct?
4. In the third picture you posted, what is the purpose of the extension of the base to the rear of the wedge box - it has chamfered edges and four bolt holes?
5. You said that you will only be drilling one hole in the ram, but there are two holes depicted in the top of the rear wall of the wedge box. Will the wedge box be bolted to the ram at these points as well? Or was it a previous design revision?
6. How will you face the front of the wedge box using the horizontal spindle? Will you bolt the ram to the table and face it that way?

I have measured from the underside of the head(where the quill disappears into the head casting) to the front of the nut on my ER40 collet chuck when it is installed and the distance is 158mm. Could someone please list this measurement for an NT30 spindle and an ER40 chuck?

Thanks to all for their efforts and suggestions. Lots of different ways to accomplish what I need - now I have to decide the best one?! I look forward to your reply Dave.

Answers not in any order
With the clamping system, there is a square hole in the top of the ram (pictured below)
In the 2nd photo you can see the bolts run down through this hole so no drilling is necessary. The previous drawing shows the mounting bolts and the new cover for the hole. I am still thinking of incorporating the cover into the design, but if I do it will be longer than 600mm which is the limit of the mills travel at the moment, so probably not.

The top surface of my ram has been machined with a planer so it is true with only very small lines under the thin paint.

I will face the front of the wedge box with the it bolted to the table and my boring head used as a fly cutter like I surfaced the plate.

I think I have covered it all, let me know if I have left something out.

Dave
Ps
From underneath my head casting to the end of the ER32 collet chuck is 120mm.

I see you edited your post with the measurement of the collet chuck.
It is 38mm longer than mine so I think you would get away with putting the bottom collar bolts into the top of the ram for a 160mm raise in head height.
Doing it this way will leave the horizontal arbor support untouched, it also gives a bit more room when tilting the head either way from the ram. I don't know about your geared head but the belt head has a recessed cover underneath, otherwise it would scrap the ram.
These plans don't come cheap, it has been a head ach working it out, the bill's in the mail,

Dave

Edit
If you have an engine crane or lifting gear, unbolt the head raise it up then sit the bottom bolts in the top holes while still holding it with the crane, and you can have a look and see what you think. I did it this way as it's only 4 bolts to undo but found the full 160mm would be to height for my 30 spindle. I could do it, but I would have to lower the quill to do some jobs to get passed the ram ways, so I would rather not. The head casting heads upward behind the quill, which gives you a bit more room between the quill and ram if the job is close.

Originally Posted by Dave J

These plans don't come cheap, it has been a head ach working it out, the bill's in the mail,

Mark..dont pay till you get the dimensioned engineering drawings.....the cheek of him...lol

has given some food for thought tho.......

Thanks Dave... and Mark

Cheers Dave - you answered all my questions there. The cheques in the mail - but I had to guess at your address - so it might take a while! I will have to sit in front of my mill for a while and ponder the best way for me. Given that I havent used the horizontal spindle - I might go with a column riser block. If I was to produce a drop kit for the free end of the horizontal spindle it could still be used. The decision I need to make is which way to go.