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Snipe and PT roller alignment

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NDRiley

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Morning All, I've recently acquired a Startrite SD310 P/T. I'm pretty pleased with it but have run into a couple of issues.

When thicknessing I was getting quite significant snipe at the end of boards. After some investigation and research on here I am pretty sure it is due to the tension springs on the outfeed roller not being as stiff as they once were (or need to be). A bit of experimentation seems to confirm that. As a test/temporary solution I've cable tied c. 1/3 of the coils together on each spring to effectively make them stiffer and that has pretty much eliminated the snipe problem. I'm now looking for some replacement springs without much luck so far - they do not appear to be "standard" and the cost of getting some custom made is prohibitive. Does anyone have any thoughts on my diagnosis of the problem and/or any suggestions for a source of new springs?

The second issue is that when conducting the investigation above, I noticed some unexpected alignment issues of the cutter block and infeed/outfeed rollers. On the SD310 (or at least the version I have) there is adjustment at one end of the cutter block to allow it to be set parallel to the thicknesser table. Once that is done the infeed and outfeed tables can be set accordingly. I've done all of that and I'm happy with it (it planes beautifully). However, there is no adjustment in the infeed or outfeed roller assemblies nor in the orientation of the thicknesser table. As a result, I have noticed the following:

1: The infeed roller is not parallel to the thicknesser table. There is a c.3mm difference from one end to the other. For narrow pieces this does not seem to cause any practical problem but with wider boards it has a tendency to twist the board laterally as it goes through the machine (I'm assuming because the roller grips tighter on one side of the board than the other). This is not too much of a problem as a gentle guiding hand on the board as it exits the machine is enough to hold it straight. However, the pedant in me would prefer it to be "right".
2: The outfeed roller is also not parallel to the thicknesser table although the discrepancy is much less pronounced (c.0.5mm).
3: The relative heights of the rollers and cutters (not the cutter block, I am measuring to the tip of the cutter and the cutters are parallel in the block) is as follows. The infeed roller is lowest. The cutters are 5.5mm to 3.5mm higher (depending on which end of the infeed roller you are referencing). The outfeed roller is higher than the infeed roller by 4.5mm/2mm (and lower than the cutters by 1mm/0.5mm). Logically I would have expected the outfeed roller to be lower (not higher) than the infeed roller as it has to engage a thinner piece of material once it has passed the cutters. I'm not sure what (if any) implications this has but would be grateful for anyone's thoughts (and critique of my logic)?

The only way I can see to "correct" these alignment issues is to use some engineer's shims to adjust the orientation of the thicknesser table either by (a) shimming where the thicknesser table bolts to the piston of the rise and fall mechanism or (b) shimming under the collar of the whole rise and fall assembly where it bolts to the casing of the machine or (c) both. Once done I would then need to realign the cutter block with the thicknesser table followed by the infeed and out feed tables and cutters in the usual way.

Again, any thoughts/observations gratefully received (even if that's to say leave well alone and stop fiddling if it's working to an acceptablle level!).

Many thanks
 

Sideways

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My suggestion: Download a copy of the manual for the sedgwick PT. If you read that it gives factory specification for things like feed roller settings relative to the arc of the cut, etc. You might find the principles are transferrable to your machine.
If I were doing the setup I'd be using an engineers dial gauge and setting everything square / coplanar / parallel within a few thou.
Tables would be set with an accurate straightedge and feeler gauges, shimmed to be level side to side and eliminate any droop.
 

Argus

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If it's of any use to this thread......

A bit of snipe always seems to be present and whilst I've managed to minimise it on my rather elderly Kity 636, some of it is a larger bite out of the leading edge, there's also an element of mechanical bruising in this area, which on those occasions where I can't sacrifice the final couple of inches, I've got most of it out with a steamy cloth and an iron before taking a plane to the remainder to remove the faint cutter ridges.

.
 

NDRiley

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My suggestion: Download a copy of the manual for the sedgwick PT. If you read that it gives factory specification for things like feed roller settings relative to the arc of the cut, etc. You might find the principles are transferrable to your machine.
If I were doing the setup I'd be using an engineers dial gauge and setting everything square / coplanar / parallel within a few thou.
Tables would be set with an accurate straightedge and feeler gauges, shimmed to be level side to side and eliminate any droop.
Thanks Sideways. I followed up your suggestion and found the Sedgwick manual to be really useful. I agree that the general principles set out in it should be transferrable. The section on the relative heights of the cutter and rollers confirms my suspicion that the outfeed roller should be slightly lower than the infeed roller. Now to work out how to achieve that on my machine!
 

Doug71

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Don't know if it helps but I set up my new to me Sedgwick planer this weekend, the previous owner said it always had bad snipe issues. I just downloaded the manual and put everything back to the factory settings and now it works perfectly :cool:

Both feed rollers were set way too low, the springs were over tensioned and the roller in the bed was stuck up about 3mm, I think someone had just kept increasing the pressure on everything to try and stop the snipe.

Get everything set up properly and you should be fine.
 

NDRiley

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Don't know if it helps but I set up my new to me Sedgwick planer this weekend, the previous owner said it always had bad snipe issues. I just downloaded the manual and put everything back to the factory settings and now it works perfectly :cool:

Both feed rollers were set way too low, the springs were over tensioned and the roller in the bed was stuck up about 3mm, I think someone had just kept increasing the pressure on everything to try and stop the snipe.

Get everything set up properly and you should be fine.
Thanks Doug, that’s interesting. I hadn’t thought about the springs being too tight rather than too slack. That could explain some of the issues I’m experiencing - the misalignment of the thicknesser table effectively making the infeed roller springs stiffer than they would otherwise be (and significantly stiffer than the springs on the outfeed roller) causing the work piece to pop up once it’s passed the infeed roller. Will investigate.
 
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