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12th Apr 2014, 03:41 PM #16Golden Member
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Michael,
Wisdom from 1945 Machinery's Handbook:
Approx PCD = OD - half belt width + (1/16" ~ 1/8")
The extra 1/16 to 1/8 depends on belt size (range A to E), so I suppose that would mean 1/16" for A belts, and presumably less for M belt sheaves.
I think that part of the approximation is due to variations in belt construction that would change the position of the neutral axis within the belt, but since for a given belt the approximation would be the same on both sheaves, the effect of the PCD approximation on speed ratio should be quite small, unless a very small sheave is used at one end - not your situation I think. Another reference gives (for A section belts) sheave PCD = sheave OD - 3/8 inch.
Re the V angle, it is generally the same for 'medium to large' size sheaves, and a greater angle for small sheaves to accommodate the bulge of the belt wall when run around a tight radius. For example A section sheaves have an included angle of 34 degrees for sheaves of 6 inch diameter and above, and 38 degrees for smaller sheaves. I think I have seen 40 degrees recommended for 'very small' sheaves (less than 3 inches diameter for A section), but cannot find the source.
Regards,
Bill
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12th Apr 2014, 05:08 PM #17
Congratulations on the new machine..
I tried those sub micron filters, and they just blocked up too quickly, the back pressure was more than the coolant pump could handle. I think the filters we are using now are 10 micron?
The wheel speed will vary as the wheel wears down, so I'd not get too fussed about speeds as long as you have the VFD you can get the exact sfpm you want.
Jayson has a Power surface grinder, but I haven't seen him around here lately.
Ray
PS. I'm willing to be that hub will be 1 1/4 ( 1.25" ) not 31mm.... 1 1/4 is a very common size for grinding arbors... if you are chasing arbors try here http://www.wmsopko.com/adapters.htm
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12th Apr 2014, 09:28 PM #18Philomath in training
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These guys say that their filters will last for months. There are actually two filters - one at 25 micron and then the 0.1. We'll have to see how it goes.
Yes, the wheel bore strictly speaking is 1 1/4".
Now - to the main story. I continued the clean up today (with it turns out a dodgy camera) so not as many pictures as I'd hoped for.
Apart from sloshing kero around, I straightened the bent screw, discovered a previous dodgy fix, discovered a neat feature and was perplexed by the way lubrication.
For anyone who feels a cyclic stiffness in a handwheel, chances are it is a bent leadscrew. This one was easy and could be done in the lathe. Before the TIR was 0.250". I simply found the high spot and gently levered with a piece of pipe. I checked with a steel rule and the bend was (as would normally be expected) at the thinnest section on the screw, just before it goes into the bearing. I stopped chasing my tail at 6 thou.
P1020190 (Medium).JPG P1020195 (Medium).JPG
I was trying to understand how the lubrication system worked and was looking at the traverse handle when I realised that it had a large amount of slop at the handle end. I disassembled and discovered that a bush had been left out of the assembly for some reason. However, when I started to examine the traverse drive I realised that there was no keyway for the wheel, the finish was different to other parts, no part number and the securing screw was wrong - it looks very much like the machine was disassembled at some stage and a whole bunch of parts lost. I think the only original item is the handle. I'm going to have to remake the gear too as it was secured onto the shaft with a (bent) dowel pin. I think I have a spare taper pin somewhere. (Photo - the only survivor; the missing bush site). The shaft is not even close to the expected tolerances and after running without a bush is not what would be regarded as a precision fit.
P1020196 (Medium).JPG
While cleaning I noticed what looked to be a slide that was horribly gummed up. I removed it and after a clean and head scratch realised that it was a slide that covered the cross feed screw when it was wound right forward. I've lubed and reinstalled it and it works quite nicely. It wasn't working before as apart from being gummed up, it had been installed backwards... The photo shows the slide along with the underside of the plate that drives it - pushed back with the feed nut, pulled forward with the lip on the rear of the table.
P1020189 (Medium).JPG
Other thing I looked at today was the lube system. Peter's shows evidence of a brass pipe to fill the felt pads for the traverse slides. There are holes to feed oil down to the cross slides but I can't see how the pockets refill on this machine. Makes me wonder whether this is an early version before the design was refined a little. The felt pads are forced up with a flat spring. Unfortunately I think it was another thing that was greased rather than oiled. As usual it seems some nipples should be oiled and some greased but I can't even find evidence that things were lubricated (except for the oil everywhere on the outside of the machine). Although there is horrible mucky grease in the oil well.
P1020188 (Medium).JPG
Michael
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12th Apr 2014, 10:01 PM #19
Congrats on the new machine Michael.
Sounds like your day was a bit like mine. It really makes you wonder what some people are thinking when they do stuff like that.
You mentioned you wanted to run the machine dry, i would highly suggest running coolant as the mess the grinding dust makes otherwise is horrible.
Cheers,
Ewan1915 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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12th Apr 2014, 10:23 PM #20Philomath in training
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A couple of people have commented along those lines.
I have been thinking along the lines of one of these -
http://www.machineryhouse.com.au/P235
but hell - that's significant proportion of the purchase cost!
Michael
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12th Apr 2014, 11:50 PM #21
Michael,
The price incudes a $120 plastic container - and its not even an esky....
You can buy their pump for $109
I think you can do a better tank yourself.
RayG replaced his pump or a while with a Bunnings $49 pump that seemed to work well too....Cheers, Joe
retired - less energy, more time to contemplate projects and more shed time....
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13th Apr 2014, 12:28 AM #22
I have a $25 bunnings pump on my B/S now, after getting the old one going it promptly up and died (got coolant in it i think). It works ok but doesn't have quite enough pressure when the head is right up. A bigger pump and a big plastic tub (i have some from bunnings that are about 40L in heavy plastic and come with a lid) should work just fine, add some baffles to the tank and some plumbing and you could easily do it for less than $100.
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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13th Apr 2014, 09:32 AM #23
With a few mods, one of these works quite well http://www.machineryhouse.com.au/A370 and you can often pick them up cheaper at auto parts places. I have one on my power hacksaw and it does a good job.
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13th Apr 2014, 06:32 PM #24Senior Member
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..............or you could just buy this :
http://www.ebay.com.au/itm/Coolant-Tank-/251503884715
greg
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13th Apr 2014, 07:53 PM #25Philomath in training
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15th Apr 2014, 10:17 PM #26Philomath in training
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Got to a little bit today. The only thing left to disassemble now is the spindle. While I would prefer not to touch it I can't see how it is lubricated so I want to check the condition and un block things if necessary.
Today I attacked the column and cleaned that up. Interesting as I found a couple of bits that I thought I would have to make sitting loose in there. The other thing that intrigues me is the type of crap that I'm finding in there.
P1020197 (Medium).JPG
It looks as if the grinder was situated for a long time next to a mill making little short chips. Most cavities on the grinder have a collection of them, generally with gummed up oil & grease.
I hope to start reassembly soon, so more photos when I do that.
Michael
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16th Apr 2014, 04:14 PM #27Most Valued Member
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16th Apr 2014, 10:55 PM #28Philomath in training
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Hmm. Sounds suspiciously like a "take yours apart so I know what mine should look like" request. It will happen in the next few days.
Tonight I did a little bit of reassembly. Someone said to me that I was crazy taking the column off - not necessarily. It was good to clean it and putting it back on was not difficult, although aligning it was. Pictured below is the method I used with a height gauge just to provide a travelling column. The column was secured with 4 SHCS, it was just loosening them, giving the column a nudge and checking again (repeat...). Bit like centring an odd bit of material in a 4 jaw or tramming a mill. I got within 2 thou over a 10" length. When you think about it, it is not vital that it is spot on square - but cosine error will come into play if it is too far out. This will be good enough until it is run. Then the plan is to put a cylindrical square on the table and check it against that.
P1020203 (Medium).JPG P1020207 (Medium).JPG
Once the column was on I started to put the vertical travel gear box on. For some reason the surface that it mounts to is scraped and the box is dowelled onto the column (that I can understand). Here we have one of those questions - the ways need oil. However, there is a grease nipple that transfers through to the cross feed nut, all the shafts with handwheels on them run in bushes and have grease nipples. In the photo of the gear box, the top nipple is for applying grease to the skew gear and the bottom nipple is to grease the shaft going through the bottom of the box (and also does the thrust bearing). The vertical slides also have grease nipples. What are opinions on the cross travel screw? Should I apply oil or grease it like everything else?
P1020208 (Medium).JPG P1020212 (Medium).JPG
The last photo is of the carriage back in the column. The interesting thing here is the spring on the screw. It looks like the spring is there so that more resistance is felt when winding up those last few mm. The silver bush at the top of the screw is dual purpose. It retains the skew gear but also has a dog point setscrew in it so that the slots on the brass collar at the bottom end of the screw hit them as a stop rather than wedge up.
P1020213 (Medium).JPG
On the information front, I found an ad dated 1965 for a small Repco surface grinder (same mag chuck size as mine) but branded Repco-Power, so it's at least older than that. The specifications it gave were brief but it had a 7" wheel and 3/4 hp motor. All food for thought. I have the national library seeing whether they have any Repco catalogues from that period too. (Repco themselves can't help much)
Bonus picture - the sliding screw protector
P1020204 (Medium).JPG
Michael
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17th Apr 2014, 12:13 PM #29
Lookin good Michael.
My cross screw is greased, it is also fully enclosed, there is a sliding ally tube at the rear and concertina covers at the front. The grease nipple is on a tube that delivers the grease between the 2 nuts.
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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17th Apr 2014, 06:08 PM #30Diamond Member
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Received the 7" grinding wheel today with thanks.
Its a White Alum Oxide 46 J bond which will be put to good use.
I have a 45 K bond (bit harder) & a 46 H bond (softer than the J)
The H bond is good for surface grinding very hard steels like HSS.
The J bond will fit between them & be very handy, thanks again.
regards
Bruce
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