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Thread: Blohm HFS6 surface grinder
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1st August 2013, 07:39 AM #31Pink 10EE owner
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A 60 grit wheel is too fine, unless you were after fine finishes on hardened steel...
You will probably find like I do, dressing the wheel is one of the most critical things to get right to get a good finish.. A wheel not dressed properly will not cut..Light red, the colour of choice for the discerning man.
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1st August 2013, 11:11 AM #32GOLD MEMBER
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Wheel Grade & Hardness
Agree with RC
Grade 60 will be a bit fine.
On my Churchill 18" by 6" Surface Grinder a 38A(white) Grade 46 K is the best for most work.
I have used a softer wheel 46 H for grinding long 18" hardened pieces of High Speed Steel.
A new wheel for my machine is 7" dia by 1/2" wide it will act "softer" as wheel diameter is reduced by dressing over time. (Lower peripheral speed)
As RC mentioned dressing technique also plays a big part in performance. A rapid cross traverse of the diamond dresser or truer will give a more free cutting wheel. Also best to use the diamond wet (with coolant)
Slow reciprocating table speed will also make the wheel act harder & increasing the reciprocating table speed will make the wheel act softer & more free cutting on hardened materials.
regards
Bruce
ps Turning back time 50 yrs to the AWA Toolroom Ashfield NSW, we used a Norton grade 120 P "Orange Wheel" for form grinding in die work, where a sharp corner was needed. Anyone know where to get hold of these wheels?
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1st August 2013, 01:09 PM #33SENIOR MEMBER
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Bruce I'm also after some 6" wheels for my little Hercus, and probably some 5" wheels for the T&C grinder, but I need to check its arbor size. So far the only source I've found is Enco in the US. If you don't have any luck finding any locally, have a look at Enco's site and if there's something there suitable I could always order it for you and you could swing past my place to collect it.
Pete
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1st August 2013, 02:13 PM #34GOLD MEMBER
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Yes bad thing to do with your finger.
At least you have that video to prove that you did have them all once if you continue to do that.
I suppose the squeal of the hydraulics would be overcome by your own squeal.
Never put your finger where you wouldn't put your pr-ck.
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1st August 2013, 03:17 PM #35
Regarding wheels, the 38a46 didn't last grinding the chuck either, but I was dressing fairly slowly. I'd like to skim it with a y feed of less than .3" or .4". The 38a I have been using is down to about 10" in dia though, I do have a new one so using that should give me more legs. Lots to learn about grinding wheels.....
Interestingly the spindle runs in plain bearings, adjustable from outside the head. They are called "precifilm" bearings, short for oil pressure film.
Cheers,
Ewan 9 finger1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.
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1st August 2013, 04:47 PM #36SENIOR MEMBER
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A couple of more tips:
1. Try the chuck mounted dresser (less prone to vibration).
2. Double balance the wheel. (balance it, dress it then rebalance) Be super patient with the balancing.
3. Try more overlap on the cross feed, with less down feed. ie minimal down feed 0.0001"
4. Soften the hydraulic return.
5. Use the down feed to break the gains of the wheel for a finer dress. say 10 dressing passes at 0.0001" down feed each time.
6. Dress slow across the wheel for finer dress 3"/min
7. Use a sharpest diamond off set to the centre line of the wheel by about 1" to get better dress.
-Josh
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1st August 2013, 04:59 PM #37Pink 10EE owner
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I should not mention that I actually feel the wheel when it is running with my finger after I dress it...
Yes I still have the normal 6 fingers on each hand...Light red, the colour of choice for the discerning man.
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1st August 2013, 05:38 PM #381915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.
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1st August 2013, 05:43 PM #39
Thanks Josh,
Good info. The hydraulic return is violent, with the coolant on full it gets waves in it you could surf on. I need to do some more reading to find out how to adjust the valve.
The diamond on the fixed dresser is pretty well stuffed, I tried the chuck mounted one and the results were better.1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.
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1st August 2013, 05:48 PM #40
One more thing re dressing, how do you touch off reliably on the diamond? I tried paper but it stayed there and the week went through it at the tip of the diamond.
Cheers,
Ew1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.
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1st August 2013, 06:19 PM #41
Hi Ewan,
Just a thought on the hydraulic noise, is it possible that there is still some air trapped in the system?
On wheel dressing, I just rotate the wheel by hand as I slowly crank the vertical down and you can feel it just start to drag. I think Josh does it the same way? Watching the video, again I think some of your passes were a bit on the heavy side, and of course when you get the final passes just before spark out, use the minimum downfeed.
Regards
Ray
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1st August 2013, 06:47 PM #42GOLD MEMBER
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Was there any particular reason why the cut wasn't done in both directions except for at the end?
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1st August 2013, 07:09 PM #43Philomath in training
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1st August 2013, 07:32 PM #44SENIOR MEMBER
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1st August 2013, 07:55 PM #45
How to get the wheel at the correct height ie just touching the diamond. I tried a tally Ho like you do when touching off the job but it didn't work.
Using an ally tube I have traced the noise to the 2 main suction (and presumably discharge depending on the table direction) lines. The rotary valve that that go into, and the ram hoses come out of) doesn't seem to be making the noise, the worse vibration is in the steel lines themselves. I doubt its air in there, I bless the system again as per the book, which should expell air out of the suction safety valves, not sure if it did but it did make "that" noise. I wonder if the suction valves have problems.
Cheers,
Ew1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.