|Oily Rag||14/04/2021 10:12:06|
480 forum posts
It sounds as if your guides are hopelessly mis-aligned. I had to resort to a little re-working to get mine to line up with the wire system, one being about 1/8th out and the other about 0.04" out in opposite directions.
The guide stays were pressings and the rollers attached onto a casting welded onto these stays. Further to this mis-alignment the guides moved when clamping the stays at differing positions. I lightly skimmed all the contact surfaces to true it all up. I concluded the welding jig (if one existed!) was being used as a door stop when my parts were made. My saw is a 'Nu Tool' (laughably from Doncaster, Ying Tong Province), my friends saw is a Sealey (part SWS v3), which has far better guide stays and adjustment for rotation of the guide rollers. This Sealey saw is a far better product than the Nu Tool and was easier to set up in a fraction of the time that mine took, it is appreciably newer though so it may well be that there is on going development back in Ying Tong!
Sounds like you need to 'bin it' or give it to someone with the patience to correct it, or correct it yourself. Look upon it as a challenge to your engineering prowess! However, I know the prevailing 'life is too short' can be a persuasive argument.
|Clive Foster||14/04/2021 10:41:06|
|2835 forum posts|
+1 for Martins verdict of mis-aligned guides.
Mine was made with similar errors but by re-working the adjuster eccentric sleeves I was able to find enough adjustment to get the blade run sufficiently close to tangential to both wheels for all to work. Not perfect because the slideways in which the guide carriers move aren't exactly in line in either plane so there is an error induced when shifting them to accommodate stock of different thickness.
I was able to get things closest to correct at maximum spacing.
Arguably the least worst option as the twisting forces imposed by the guides on the blade as it comes off the top wheel will be maximum at that setting. Moving the guide down for thinner stock lets the twist occur over a longer length of blade so twist forces should be less. Hopefully allowing the system to cope with more residual error.
Had I known about arranging things to let the blade to run true between the wheels first then setting the guides to the blades I'd have got it to OK a darn sight faster! Now I have a Bridgeport its tempting to take the main casting off and re-machine it so everything starts out aligned. Then make new guide carriers to suit.
Unlike Martins Nu-Tool version my Alpine, and presumably yours, has castings for all structural components.
Edited By Clive Foster on 14/04/2021 10:41:43
|Nigel Graham 2||14/04/2021 12:24:43|
|1706 forum posts|
The guides do seem mi-aligned but it's hard to see how wear-and-tear could cause it because they are quite rugged castings and you don't move them all that often.
The inner guide rollers are on fixed axles, and seem to be the ones that twist the blade. Their positions cannot be moved relatively to the machine's axis.
The outer ones are on eccentrics to allow them to be adjusted so they don't contact the blade, or by no more than a very light touch given by a swarf clearance gap.
BUT.... see below about that gap.
The guides' carriers are all castings, as Clive goes on to say. The only pressings on these Taiwanese machines are the rather crude stand and a few small details. Some parts are formed from thicker plate and bar, but not ones that are causing problems.
" Sounds like you need to 'bin it' or give it to someone with the patience to correct it, or correct it yourself.
Errrr. eh? I'm not sure how to take that middle clause, but with a new saw costing around £500, I am trying to correct it if it's at all possible and if it won't become a long-term project. I have the patience, thank you, but not for lost causes, as I fear this may be.
The inner guide rollers seem to be the ones that push the blade into line - but possibly not the intended line, and these are not adjustable.
The drive end guide's lengthwise adjustment is only enough to clear the vice, and is the one that really creates the severe twist.
The top, or outer-end, guide has the more adjustment and is kinder to the blade; but still has a fairly short range. I don't like using the machine in vertical mode because that guide does not come close to the table.
I have just paused to download the machines' manuals from Machine Mart's on-line catalogue. Same saw, in both Clarke and Draper colours; but detail differences suggest the Draper version is of slightly higher quality though basically the same thing. For example, Clarke's guide-bar clamps are hexagon-headed set-screws; the Draper and Alpine have large hand-wheels on the screws.
The adjustable guide-roller is called the "outer" one, and specified as 0.001" from the surface of a 0.025" thick blade, not the 0.005 - 0.010" that John Pitkin says. So who is right? The manufacturers or a user's handbook covering more than one make and pattern? One thou is tight. Five thou maybe, but ten thou won't do much guiding except to a bumpy weld.
The Clarke manual gives instructions on tensioning the blade with or without a tension-gauge. (Some industrial band-saws have a tension-indicator built in. Also, they don't seem to twist the blade through quite such a steep angle.)
The Draper instructions are slightly less comprehensive, and the screen definition of their photos is low, but a test showed fairly legible printing, albeit shrunken. They advise only tensioning the blade enough to prevent slip.
The manuals say the blade should just touch the flanges on the pulley, but not run hard against them.
I'd wondered if a previous owner had dismantled and inadvertently re-assembled the rollers on the wrong sides of their castings, but the manuals proved this not so.
I might now have distorted or stretched my last blade enough to be unreliable as an adjustment-gauge, so will have to obtain new ones before going much further. I can though try to test and if necessary correct the wheels' mutual alignment.
|john fletcher 1||14/04/2021 12:43:29|
|724 forum posts|
I notice several readers have mentioned broken saw blades. Years ago there was an article in ME on repairing band saw blades and I have been following the instruction with success. Following the instructions, I made a little jig to enable me to chamfer the broken ends using a belt sander. Using another jig the two ends are then clamped together with a very small gap and are Silver soldered together. I use wire type Silver solder. John
|John Rutzen||14/04/2021 12:48:28|
|332 forum posts|
I have one of these saws and wouldn't be without it. Mine is a Draper but they are all pretty much alike. I don't find it difficult to change the blades, I usually put the blades into the guide rollers first and then twist the blade to go over the wheels, having slacked off the tensioner of course. I dispensed with the cover years ago, if the blade breaks or comes off then it just stops. Like others have said don't have the rollers tight on the blade, it should be easy to slide the blade between them. I only buy the carbon steel blades, they last a long time provided you have the saw on it's slowest speed.
|Clive Foster||14/04/2021 13:35:39|
|2835 forum posts|
I should have the Alpine saw manual somewhere safe and could scan it if you'd like a copy. Don't recall seeing it this century but fairly sure I know where it ought to be.
I've fitted eccentric adjusters to all four of my guide wheels made to give the maximum possible throw without serious re-design. Looks like I needed all that throw to get to a workable set-up.
The standard two guide bearings fixed and two adjustable set-up is basically to accommodate variations in blade thickness. The fixed mounts are supposed to be on the inside to define the blade path. That design assumes the saw is made with sufficient accuracy to put the fixed bearings in the right place. Not so with mine. Looking at it now it appears that the constructional errors add up to cumulative errors in guide position approaching 1/4" out of line.
As I said earlier mine worked adequately as standard once a satisfactory adjustment had been achieved for several years before misbehaving. I can only assume that it took several years for wear and other strain related issues to accumulate to a level preventing the standard set up from coping with mis-alignment.
|Nigel Graham 2||14/04/2021 21:25:03|
|1706 forum posts|
I felt well enough today to have another look at the machine.
Removing the top pulley, I realised I could fit a pair of simple guides for the axle-block, made from bright steel-angle, on the interior of the bow.
They share the tapped holes already there for securing the two retaining-strips for the block, held on the outside of the bow by M6 screws. The screw lengths were only about half the thickness of the frame casting, so I could tap the holes right though and secure both pairs of parts independently.
I drilled the holes in the angles generously over-size and slotted them slightly, for simple adjustment.
This removed the swinging effect that had made life right difficult.
To set the pulley along its stub-axle, I replaced the spacer cut from an odd length of tube, with steel and PTFE washers, the latter from one of those assortment boxes from Aldis or a motor-parts shop. I will have to revisit it, as I think the pulley is rubbing slightly. It would make sense to measure and turn a proper spacer from brass or something.
Watching it running - socially distanced as I had the door open - it seemed to track OK though.
Next was to fit and set the guides as best I could, but I think I distorted the blade quite badly with all this fafffing, so really, can't adjust the machine properly until I can obtain a new blade. Clamping the guide-carriers still seems to pull them out of line though, and the blade emerges slightly twisted from the rollers .
Even so, It cut reasonably squarely through a piece of 25 X 12m, black mild-steel; and came to rest with a much smaller gap than previously, between blade and steel.
I stopped there while the going was good.....
|vic francis||22/04/2021 10:51:48|
|73 forum posts|
Hi Nigel, speedy recovery, err well I used said bandsaw, think it was a pinacle? Early 4.5 hori / vertical typical design but after experimentation in setting esp the crown wheel used it alot ie daily! And with the thin cork on the lower drive wheel it hardly broke any blades, perhaps one per year! I used very little blade tension.... so blades lasted a long time, unless snagged...and a reasonable downcut pressure to avoid rubbing.I used it for 6 years plus as well! It came from another dept so it was second hand .Useable when I got it as well.I always cut dry or friction would be lost...The procurement woman was tight about buying things, ( packs of blades) so I made sure things lasted! The sort of work it did was bar and tube upto 30mm ; I once cut 70mm bronze bar ! But best to turn it...There is a quality difference between blades, the thicker blade was superior, and fine pitch was preferred. The workshop was too small to have a decent cutoff type so I made do... I also improved the work holding clamp... Evo stick glued the cork to the wheel... I tried rubber originally, but creep occurred! , cork was the best; boiler insulation would be perfect around 2mm thick.
|Nigel Graham 2||24/04/2021 23:00:10|
|1706 forum posts|
John Rutzen -
I have the handbooks for the Draper and Clarke saws. Both specify a 0.001" clearance for the blade - which does not allow much for a thicker weld.
John Fletcher -
Brings back memories... I was the materials store-keeper for a screen-printer manufacturer for some years, back in the 1980s. Until the company bought a band-saw blade welder, I had to use silver-soldering on a simple jig to make up blades from stock rolls in various tooth-counts, as you describe. That was for a multi-speed Startrite vertical saw I used for plate-cutting from 16mm alum-alloy, to quarter-inch gauge plate - the latter was used for big plate-cams, before the stepper-motors and electronics in the very sophisticated machines the firm makes now. (A hacksawing machine with roller-bed dealt with the bar stock.)
Finding the Clarke and Draper manuals seems to cover it, but thank you for the offer. They are all basically the same machine with only detail differences.
You may have hit the rivet on the head with my saw: as with yours, wear and tear catching up with it. That could account for the cut being inside the rest line of the blade by an appreciable amount, although I seem to have reduced that a bit.
The blade-guide bars are hardly exemplars of precision-machining, and one rocked quite noticeably on a surface-plate. I was able to cure that to some extent by careful filing, which revealed enormous machining chatter-marks. The slide-ways in the frame look reasonably well machined, but I could test them with a suitable straight-edge.
Rather crocked at the moment, I am not doing much in the workshop, but you've given me a clue as to what is still going wrong. I have noticed one of the guides moves noticeably sideways when I tighten its clamp.
Thank you for your best wishes. It won't be speedy I'm afraid, and it's knocked my workshop activities right back because I cannot stand at a machine for long.
I will bear in mind what you say, of a cork tyre. For the moment I want to fit a new blade without modification as I think the existing one, my last, is too distorted to give a fair test to the machine. It will cut but meanders rather wonderfully. I have some thin cork sheet I could probably use.
I buy the blades from the local 'Toolstation' but unless I can make up enough order for delivery to be worthwhile that's out of reach. I dare not risk driving, even the couple of miles each way, for the time being.
|Cornish Jack||27/05/2021 19:07:58|
|1218 forum posts|
Axminster horizontal/vertical two wheel bandsaw. The urethane 'tyre' on the motor drive wheel has stretched and had to be shortened and 'bodged'. with cyano. Works as a temporary fix, but I would like to fit a new one. The only ones I have found so far, come from the States and need a mortgage!. Does anyone have a source which will leave enough change to buy food !
Edited By Cornish Jack on 27/05/2021 19:08:17
|not done it yet||27/05/2021 21:33:30|
|6321 forum posts|
Don’t axminster carry spare parts or info on sourcing materials to repair their products?
|Cornish Jack||28/05/2021 00:05:28|
|1218 forum posts|
Thank you NDIY - It was a thought that had flickered through my sub-consciousness before embarking on a world-wide search !
In lieu of any helpful suggestions, for anyone with similar woes, cutting the expanded tyre, and glueing the cut ends to fit, does provide a temporary fix.
|Howard Lewis||28/05/2021 09:21:25|
|5298 forum posts|
Interesting, the comments re setting the giude rollers clear of the blade!
I set mine to bear against the blade, without problems, but on my Warco one, all rollers are adjustable.
I would have thought that having the rollers clear of the blade would allow it to twist, or move from side to side.
A machine with backlash is unlikely to cut accurately, or consistently.
If it cuts in an arc, you may be loading the blade down too hard.
As long as I do not overdo the down feed pressure, once set up, with the blade tensioned, using the Jaques Maurel Tensionmeter, it cuts pretty accurately, and instead of blades breaking, they wear out!
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