Meyer-Mace Isotopic NMR Generator

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Peterae

Re: Meyer-Mace Isotropic NMR Generator « Reply #175 on: 2016-02-07, 12:03:40 »

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Quote

Was the turn spacing equal to the wire thickness?

It's more like 1.5 times gap space between wire, i used plastic coil space strips and only had that size so could not control the gap.

Quote from: Peterae on Today at 10:20:12

Quote

49.4-45.9=3.5
45.9-42.5=3.4
bandwidth 6.9MHz

Measured like this?
yes

Quote

According to this, the permeability of 99.8% iron should be around 5000.

Sorry i added another post and then edited as you were posting this, if you go back you will see i added another post after the one you replied to.

verpies

Re: Meyer-Mace Isotropic NMR Generator « Reply #176 on: 2016-02-07, 12:21:51 »

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Quote from: Peterae on 2016-02-07, 12:03:40

Sorry i added another post and then edited as you were posting this, if you go back you will see i added another post after the one you replied to.

I edited my previous post, too...

Peterae	Re: Meyer-Mace Isotropic NMR Generator « Reply #177 on: 2016-02-07, 13:09:28 »
Group: Administrator Hero Member Posts: 3975	Sorry run out of time today. I am wondering if i need to carry out some tests on this iron core as suggested here http://meettechniek.info/passive/magnetic-permeability.html The Driving dependence permeability test would be interesting at 45MHz although it suggests 100Hz to 1Khz for test. With my meter set to 120Hz i should be reading mH for that bias coil and i am not, instead i am only reading uH, i could probably hold a UGN3503 at the end of the iron rod if i take one end of the core supports off to measure the flux strength to compare the measured flux. Does a core not need to be closed for a coil to see the full permeability of the core, maybe the air gap at one end is introducing a series permeability affecting the value. Personally i would rely on the measured inductance value, and in that case i need to make a coil with the appropriate measured mH value, that way i know i have the 0.5T flux level for the used 1Amp current.

verpies	Re: Meyer-Mace Isotropic NMR Generator « Reply #178 on: 2016-02-07, 14:46:15 »
Group: Professor Hero Member Posts: 3670	Quote from: Peterae on 2016-02-07, 13:09:28 The Driving dependence permeability test would be interesting at 45MHz although it suggests 100Hz to 1Khz for test. I think so, too. Quote from: Peterae on 2016-02-07, 13:09:28 With my meter set to 120Hz i should be reading mH for that bias coil and i am not, instead i am only reading uH, i could probably hold a UGN3503 at the end of the iron rod if i take one end of the core supports off to measure the flux strength to compare the measured flux. Yes, but the best location for the magnetic flux density sensor is in the air gap. Quote from: Peterae on 2016-02-07, 13:09:28 Does a core not need to be closed for a coil to see the full permeability of the core, Yes Quote from: Peterae on 2016-02-07, 13:09:28 maybe the air gap at one end is introducing a series permeability affecting the value. I am sure it is but not enough to bring the combined relative permeability down to 1. The gap area is a surface of a cylinder in the hole. Quote from: Peterae on 2016-02-07, 13:09:28 Personally i would rely on the measured inductance value, and in that case i need to make a coil with the appropriate measured mH value, that way i know i have the 0.5T flux level for the used 1Amp current. The magnetic flux density sensor measurement in the air gap is an ultimate direct measurement of a constant field at DC.

Peterae	Re: Meyer-Mace Isotropic NMR Generator « Reply #179 on: 2016-02-07, 19:26:08 »
Group: Administrator Hero Member Posts: 3975	Quote Yes, but the best location for the magnetic flux density sensor is in the air gap. I dont think the UGN3503 is small enough to fit in the gap, as the gap is slightly under 1mm and is circular in shape, and anyway surely the magnetic field strength will be spread around the circumference of the core and gapped end plate so would only measure a small portion of the field. maybe the thing to do is carry out the dependence permeability test with and without the end plate to see what difference there is. I'm away for 4 days as from tomorrow, not that that makes much difference as i only get weekends on this anyway. Quote I am sure it is but not enough to bring the combined relative permeability down to 1. A bit of exaggeration on my part, it is certainly above 1 but does not look much above, i can work on this by looking at my measured inductance versus calculated.

verpies	Re: Meyer-Mace Isotropic NMR Generator « Reply #180 on: 2016-02-07, 21:25:56 »
Group: Professor Hero Member Posts: 3670	Quote from: Peterae on 2016-02-07, 19:26:08 I dont think the UGN3503 is small enough to fit in the gap, I was afraid of that. Quote from: Peterae on 2016-02-07, 19:26:08 and anyway surely the magnetic field strength will be spread around the circumference of the core and gapped end plate so would only measure a small portion of the field. Flux will be spread this way, not flux density, which is already flux divided by area. Quote from: Peterae on 2016-02-07, 19:26:08 maybe the thing to do is carry out the dependence permeability test with and without the end plate to see what difference there is. You could do that. Did you try inserting a ferrite rod instead of the iron rod to see what difference the absence of eddy current makes?

Peterae	Re: Meyer-Mace Isotropic NMR Generator « Reply #181 on: 2016-02-07, 22:08:09 »
Group: Administrator Hero Member Posts: 3975	Quote Did you try inserting a ferrite rod instead of the iron rod to see what difference the absence of eddy current makes? Ran out of time, will try this next weekend I have a ferrite rod aerial, i will try this ferrite rod.

Peterae	Re: Meyer-Mace Isotropic NMR Generator « Reply #182 on: 2016-02-12, 17:01:40 »
Group: Administrator Hero Member Posts: 3975	So carrying on from last time. I know that my bias coil has 40T and it's inner diameter is 30mm and it's 1mm wire, giving a loop diameter of 31mm on the core i get 147uH and as an air core i get 61uH Using the calc here http://www.eeweb.com/toolbox/coil-inductance So running the calcs for air i get 0.0000753 H or 75.3uH (measured 61uH) Looks good for air with the core i get 147uH which gives me a relative permeability of about 1.4 So next to carry out the tests here, so i wound 150Turns of wire onto the iron core. I measured the total magnetic path length as 330mm so lc = 330mm Area of core with diameter of 20mm = 314mm2 so Ac=0.000314 I ran the system at 10KHz to get good amplitude for VL & IL and am using Rms voltages for calcs IL=VR/R IL=50.3mV/10 IL=0.00503 Amps therefore uc (absolute permeability)= VLlc / IL Ac * N2 * 2pi * f uc = (78.2mv * 330mm) / ( 0.00503 * 0.000314 * 150^2 * 2pi * 10000) uc = 0.025806 / 2232.85242 uc = 1.15574 x 10-5 H·m−1 µr = µc / µ0 µr = 1.15574 x 10-5 / 1.2566370614 ×10−6 ur = 9.197 Here's the experiment and calcs page, i did Fig 1 test circuit. http://meettechniek.info/passive/magnetic-permeability.html EDIT OK i just re did the experiment at 100Hz IL=VR/R IL = 52.5mv / 10 IL = 0.00525 Amps therefore uc (absolute permeability)= VLlc / IL Ac * N2 * 2pi * f uc = 14.9mV * 330mm / 0.00525 * 0.000314 * 150^2 * 2pi * 100 uc = 0.004917 / 23.3051197 uc = 2.1098 x10-4 µr = µc / µ0 ur = 2.1098 x10-4/ 1.2566370614 ×10−6 ur = 167.9 OK worked out my problem Ac wrong, so have amended my results above ------------------------ Meyer-Mace Isotopic NMR Generator 10khz1.png (56.44 kB, 800x480 - viewed 847 times.) Meyer-Mace Isotopic NMR Generator 10khz2.png (57.31 kB, 800x480 - viewed 837 times.) Meyer-Mace Isotopic NMR Generator 100Hz1.png (62.49 kB, 800x480 - viewed 802 times.) Meyer-Mace Isotopic NMR Generator 100Hz2.png (59.54 kB, 800x480 - viewed 812 times.) « Last Edit: 2016-02-12, 20:20:03 by Peterae »

Peterae	Re: Meyer-Mace Isotropic NMR Generator « Reply #183 on: 2016-02-13, 17:35:28 »
Group: Administrator Hero Member Posts: 3975	Done a whole range of tests on the core today at different frequencies. Here's the openoffice calc sheet and a graph Frequency (Hz) ur Relative Permeability 1 85104.2087086032 10 7009.5528736088 20 3545.9746457914 40 1782.2443764725 100 726.9583944169 200 373.7802630722 400 193.9317102927 800 103.0953956195 1000 84.8735739967 2000 46.6126662721 4000 26.8530030133 8000 16.0437830316 10000 14.0047045292 20000 8.8614478555 50000 5.1610923318 100000 3.5894904096 200000 2.0834773901 500000 1.485185365 1000000 1.1437175365 2000000 0.9647272589 5000000 0.7221140347 10000000 0.1641680225 15000000 0.0629936064 20000000 0.0866588487 25000000 0.0052553037 Not sure what to make of the below 1 Relative Permeability values, i looked this up and it only happens with Super Conductors, i think it is more likely the losses get so big that the results are swayed off track. I used Log Axes for X & Y so we could see the data. ------------------------ Meyer-Mace Isotopic NMR Generator Freqvsperm.jpg (34.1 kB, 801x492 - viewed 738 times.) RelativePerm.ods (21.78 kB - downloaded 268 times.)

Peterae	Re: Meyer-Mace Isotropic NMR Generator « Reply #184 on: 2016-02-13, 21:48:29 »
Group: Administrator Hero Member Posts: 3975	Not sure how applicable this is for our calculations but i found this formulae http://www.micrometals.com/images/curves/SIformulapg29.gif and considering we were told Quote The second coil (4) is traversed by a sinusoidal wave of 21 MHz and 10-4 Tesla power which is a nuclear magnetic resonance activator allowing 180 ° rotation of the nuclear spine So using my 4 Turn coil and core cross section i now know that if our coil has a RMS voltage of 30V at 45MHz then we will have a B flux max peak of 0.0001195463 Teslas which matches our required Flux. I used 4.44 instead of 4 in the formulae this allows me to use Vrms instead of Vavg ------------------------ Meyer-Mace Isotopic NMR Generator SIformulapg29.gif (5.05 kB, 400x213 - viewed 523 times.)

Peterae	Re: Meyer-Mace Isotropic NMR Generator « Reply #185 on: 2016-02-14, 16:43:23 »
Group: Administrator Hero Member Posts: 3975	I cannot seem to find any of my UGN3503 hall effect sensors so have ordered some for B field tests. I connected my 1.5 Watt amplifier up to my DDS and connected the 4 Turn coil to the Amplifier output to see what sort of matching issues i might have. I uses 2 x 1.1 Ohm resistors in parallel to form a 0.55Ohm for current sensing, still 2 high a value really so will order some 0.1 Ohm resistors. Anyway below are some scope shots with the 4 Turn coil, i get some sinewave distortion at 44.5MHz even after tuning the variable capacitor, but at higher frequencies after retuning the cap this harmonic distortion seems to go away, i can adjust the DDS level to which i drive the pre amplifier and that does not alter the situation. The scope shots are taken at different frequencies as can been seen on the scope frequency counter in each picture. Cyan Chan is across the LC, Yellow from ground side of LC to series resistor side of LC, Math subtracts the 2 to give the wave across the current sense 0.55 Ohm resistor. If i go by the previous post and calculate the Bmax Field i get QuickPrint7 = 34.5 uT QuickPrint8 = 32 uT QuickPrint11 = 46 uT So i am well under the requirements for the required 100uT but not by much considering i am running at 1.5 Watts I need to understand the distortion with 44.5MHz, the cyan channel is fine so that's across LC, the yellow is across the R-LC and the distortion can be seen, i have a feeling it's because the 0.55 Ohms CSR is too big, so must get a 0.1 Ohm ------------------------ Meyer-Mace Isotopic NMR Generator DS1Z_QuickPrint5.png (62.33 kB, 800x480 - viewed 549 times.) Meyer-Mace Isotopic NMR Generator DS1Z_QuickPrint6.png (59.31 kB, 800x480 - viewed 540 times.) Meyer-Mace Isotopic NMR Generator DS1Z_QuickPrint7.png (59.69 kB, 800x480 - viewed 506 times.) Meyer-Mace Isotopic NMR Generator DS1Z_QuickPrint8.png (67.7 kB, 800x480 - viewed 524 times.) Meyer-Mace Isotopic NMR Generator DS1Z_QuickPrint9.png (79.46 kB, 800x480 - viewed 516 times.) Meyer-Mace Isotopic NMR Generator DS1Z_QuickPrint10.png (65.23 kB, 800x480 - viewed 519 times.) Meyer-Mace Isotopic NMR Generator DS1Z_QuickPrint11.png (66.94 kB, 800x480 - viewed 497 times.) Meyer-Mace Isotopic NMR Generator 20160214_161021.jpg (2945.32 kB, 1920x2560 - viewed 566 times.) Meyer-Mace Isotopic NMR Generator 20160214_161033.jpg (2854.62 kB, 2560x1920 - viewed 549 times.) « Last Edit: 2016-02-20, 11:47:55 by Peterae »

verpies	Re: Meyer-Mace Isotropic NMR Generator « Reply #186 on: 2016-02-17, 16:37:40 »
Group: Professor Hero Member Posts: 3670	Quote from: Peterae on 2016-02-12, 17:01:40 with the core i get 147uH which gives me a relative permeability of about 1.4 But this is a sum of the positive permeability of iron and negative permeability caused by eddy currents. Quote from: Peterae on 2016-02-12, 17:01:40 I measured the total magnetic path length as 330mm so lc = 330mm How did you measure that with a non-closed magnetic path? You can directly include the width of an air gap only when the air gap is very small and flux fringing does not effect the effective gap area significantly. However your air gap is huge because you are using a rod for a core! See the section titled "Gap area correction" in this paper. ------------------------ Flyback magnetics slup127.pdf (2101.19 kB - downloaded 456 times.) « Last Edit: 2016-02-17, 18:01:05 by verpies »

Peterae	Re: Meyer-Mace Isotropic NMR Generator « Reply #187 on: 2016-02-17, 18:25:45 »
Group: Administrator Hero Member Posts: 3975	Quote But this is a sum of the positive permeability of iron and negative permeability caused by eddy currents. I will test the B field strength as soon as i get the UGN3503 Hall effect sensors at DC for the bias coil Quote How did you measure that with a non-closed magnetic path? There were details on the website on where to use, it is basically a path all the way around the iron rod down the left side along bottom and up the right side back to the iron rod and the centre line is used in each case. So cannot remember if i built it to this early drawing but taking this drawing for example then we would have 100mm for the top iron bar, 100mm for the bottom, 60mm for left and right, for this drawing it would be 320mm so it appears my build was a slightly different size, i also went on to use a 20mm diameter iron rod instead of the drawings 18mm

verpies	Re: Meyer-Mace Isotropic NMR Generator « Reply #188 on: 2016-02-20, 03:19:02 »
Group: Professor Hero Member Posts: 3670	Quote from: Peterae on 2016-02-17, 18:25:45 There were details on the website on where to use, it is basically a path all the way around the iron rod down the left side along bottom and up the right side back to the iron rod and the center line is used in each case. But the yoke walls are pretty thin so there will be a significant leakage flux like on the diagram below: ------------------------ Meyer-Mace Isotopic NMR Generator Leakage Flux.png (47.27 kB, 406x370 - viewed 514 times.)

verpies	Re: Meyer-Mace Isotropic NMR Generator « Reply #189 on: 2016-02-20, 03:26:56 »
Group: Professor Hero Member Posts: 3670	Quote from: Peterae on 2016-02-14, 16:43:23 Anyway below are some scope shots with the 4 Turn coil, i get some sinewave distortion at 44.5MHz even after tuning the variable capacitor, Any indication of something different at this Fe NMR frequency is hopeful. What is the bandwidth of this distortion? What I am really missing is the permeability tabulations with an air coil, ferrite rod and even a copper rod. This would allow me to subtract the response of the coil itself from the response of the rod, to obtain the contribution of the rod.

Peterae	Re: Meyer-Mace Isotropic NMR Generator « Reply #190 on: 2016-02-20, 08:01:15 »
Group: Administrator Hero Member Posts: 3975	Quote What I am really missing is the permeability tabulations with an air coil, ferrite rod and even a copper rod. So what is the closed flux path length for a Rod? When i know that then i could try it, or do you mean push a copper rod into my iron U shaped frame ? During the week i ordered some enamelled wire to make some more litz, i also ordered some Bronze ribbon wire, Bronze has 3 times the skin depth and the ribbon maximises the surface area. I want to try a 10 turn coil, meyer used 22 Turns at 23MHz which i find interesting. Quote Any indication of something different at this Fe NMR frequency is hopeful. What is the bandwidth of this distortion? No it's not at exactly 45Mhz but appears below around 50Mhz, ~~the current waveform is undistorted but the voltage gets misshapen~~, probably some sort of impedance mismatch. EDIT Dam i have my traces the wrong way around in this post and with the waveforms post 185 (now corrected). Yellow is the Voltage R-LC, Cyan is across the Voltage across LC. So my voltage across LC is good, and my Math purple (R-LC - LC) has distortion, so it's the current thats distorted not the LC Voltage. I will go back to post 185 and change the scope colours to correct them. « Last Edit: 2016-02-20, 10:28:11 by Peterae »

Smudge

Re: Meyer-Mace Isotropic NMR Generator « Reply #191 on: 2016-02-20, 09:30:58 »

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Quote from: verpies on 2016-02-20, 03:26:56

Any indication of something different at this Fe NMR frequency is hopeful. What is the bandwidth of this distortion?

What I am really missing is the permeability tabulations with an air coil, ferrite rod and even a copper rod.

This would allow me to subtract the response of the coil itself from the response of the rod, to obtain the contribution of the rod.

Don't know whether section 1.3 of my paper is of any help. This allows you to calculate inductance for single layer coils using Nagaoka's geometric factor. With permeable cores a more accurate calculation would use published demagnetization factors for rods in place of Nagaoka's. The effect of a copper rod could be modeled by giving it a permeability below 1 but the actual value to use will depend on the frequency.

Smudge

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Energy around Coils and Magnets.pdf (216.61 kB - downloaded 299 times.)

verpies	Re: Meyer-Mace Isotropic NMR Generator « Reply #192 on: 2016-02-20, 10:44:16 »
Group: Professor Hero Member Posts: 3670	Quote from: Smudge on 2016-02-20, 09:30:58 Don't know whether section 1.3 of my paper is of any help. This allows you to calculate inductance for single layer coils using Nagaoka's geometric factor. Of course it will be but not completely because the eddy currents in the solid iron rod and steel yoke are repelling the magnetic flux. If you look above at Peterae's tabulation of solid iron's permeability at different frequencies, then you will see that above certain frequencies the eddy currents start to dominate the ferromagnetism and yield a relative permeability below 1. Quote from: Smudge on 2016-02-20, 09:30:58 With permeable cores a more accurate calculation would use published demagnetization factors for rods in place of Nagaoka's. ...but what about the frequency dependent permeability of theses cores? How to model that for the shape of the yoke?

Smudge	Re: Meyer-Mace Isotropic NMR Generator « Reply #193 on: 2016-02-20, 10:59:34 »
Group: Professor Hero Member Posts: 1961	Just to clarify my last post. Nagaoka's formula (1) gives you the inductance of an air cored coil. That coil has an internal reluctance in series with the return path outside the coil. This is modeled as two reluctances in series (figure 2) driven by the coil mmf. Equation (9) is the inductance for those two reluctances and equations (3) and (10) gives you those two reluctances. With other than air as the core you use the permeability to change the internal reluctance from air to a new value, ending up with equation (12) for the inductance. For muR=1 (12) reverts back to (1). To model the effect of a copper coil, at low frequencies the copper reduces the inductance to almost zero. Putting muR as zero into (12) gives you zero inductance. The real effect will be somewhere in between zero and the air cored inductance which you get by putting muR between 0 and 1. Can't tell you what value to use but it could be got by doing some measurements. Smudge

Peterae	Re: Meyer-Mace Isotropic NMR Generator « Reply #194 on: 2016-02-20, 12:05:21 »
Group: Administrator Hero Member Posts: 3975	Smudge For a picture of my Setup see here http://www.overunityresearch.com/index.php?topic=3107.msg54334#msg54334 I need to design a DC Bias coil to give 0.5T but i dont know what to use for my permeability. I could just wind some wire and measure the Inductance using my LCR meter and try to work out the B Field from the measure Inductance, but my meter only tests at 100Hz,120Hz & 10KHz Any pointer here would be good, i am hoping to use 1mm enameled copper at 1 Amp current I am going to do some sniffing tests using a ratiometric hall sensor but to do this i have to remove one side of my U shaped frame to get the hall near the magnetic path and so this test will not represent my true U frame flux.

verpies	Re: Meyer-Mace Isotropic NMR Generator « Reply #195 on: 2016-02-20, 12:32:58 »
Group: Professor Hero Member Posts: 3670	@Smudge What do you think of linearly interpolating this μ_r vs. f curve, all the way down to DC in order to obtain the permeability, that Peterae can use for his DC bias coil calculations ? Can you think of a better method ?

Peterae	Re: Meyer-Mace Isotropic NMR Generator « Reply #196 on: 2016-02-20, 13:16:14 »
Group: Administrator Hero Member Posts: 3975	OK some DC Bias measurements with a AH350 The Bias coil was driven using 5Amps for this test The AH350 is ratiometric picture QP1 shows a DC offset of 2.62V at zero flux I found the maximum Flux on the iron core was at the outer circumference and QP2 shows a voltage of 3.16V So we have 3.16V-2.62V=540mV According to the datasheet when driven at 5v the AH350 has a sensitivity of 2.2mv/G so therefore we have 245G Tesla = Gauss/10000 so we have a flux B of 0.024T so no where near our required 0.5T ------------------------ Meyer-Mace Isotopic NMR Generator QP1.png (41.61 kB, 800x480 - viewed 495 times.) Meyer-Mace Isotopic NMR Generator QP2.png (42.5 kB, 800x480 - viewed 500 times.) Meyer-Mace Isotopic NMR Generator 20160220_124644[1].jpg (2593.76 kB, 2560x1920 - viewed 530 times.) « Last Edit: 2016-02-20, 14:43:17 by Peterae »

Peterae	Re: Meyer-Mace Isotropic NMR Generator « Reply #197 on: 2016-02-20, 15:13:39 »
Group: Administrator Hero Member Posts: 3975	OK built a 10 Turn Bronze wire tape coil see picture Here's some scope shots as well, i am now using the 1 Ohm series LC Resistor again for current monitoring, it has better a resolution Each shot was taken at different frequencies to show distortion and how it changes with frequency. QuickPrint1 was interesting, if i set the DDS to 100Mhz i can then use the variable cap to set the operating frequency with this coil ------------------------ Meyer-Mace Isotopic NMR Generator 20160220_143011[1].jpg (2692.34 kB, 2560x1920 - viewed 518 times.) Meyer-Mace Isotopic NMR Generator DS1Z_QuickPrint1.png (84.1 kB, 800x480 - viewed 516 times.) Meyer-Mace Isotopic NMR Generator DS1Z_QuickPrint2.png (74.98 kB, 800x480 - viewed 476 times.) Meyer-Mace Isotopic NMR Generator DS1Z_QuickPrint3.png (73.34 kB, 800x480 - viewed 492 times.) Meyer-Mace Isotopic NMR Generator DS1Z_QuickPrint4.png (79.01 kB, 800x480 - viewed 481 times.) Meyer-Mace Isotopic NMR Generator DS1Z_QuickPrint5.png (71.41 kB, 800x480 - viewed 491 times.)

verpies	Re: Meyer-Mace Isotropic NMR Generator « Reply #198 on: 2016-02-20, 15:17:44 »
Group: Professor Hero Member Posts: 3670	The flux density measurement would be much more accurate (and larger) if you'd placed the sensor like on the diagram below in the green zone. Optionally, you could plug the hole in the yoke with a second piece of that iron rod, if you have any left, so the hole is not in the way and the long rod does not have to be skewed like that. ------------------------ Meyer-Mace Isotopic NMR Generator UGN placement.png (9.22 kB, 952x261 - viewed 534 times.)

Peterae	Re: Meyer-Mace Isotropic NMR Generator « Reply #199 on: 2016-02-20, 15:30:16 »
Group: Administrator Hero Member Posts: 3975	Hi verpies yes that's a good idea, but i dont have a press to push the pure iron rod along a bit, and i just tried hitting it to move it and it wont budge, must be a good interference fit due to my good engineering skills I do have mild steel the diameter to plug the hole. If i can find a way to move it i will give it a go.