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Hacksaw blade declogger

Swarf removal device attached to the saw
  (+7, -1)
(+7, -1)
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When cutting thick pieces of relatively soft metal (e.g. 8mm aluminium alloy sheet) with some hacksaw blades, the swarf has a tendency to gather between the teeth, thus slowing the cutting. The normal solution to this is to change the blade to a coarser one, but what happens when one does not possess such a blade?

I propose a device which will run along the blade to remove this swarf, thus allowing a finer blade to be used without the bother of changing a blade - although in the case of some quite thick pieces, the blade may clog by the time it reaches the other side of the workpiece, in which case, the more old-fashioned solution must be used.

The [link] shows a diagram of the device - it might be a bit complicated to work it out from this description.

The invention consists of three rollers, a welded frame (some strengthening bracing may be added, but in the diagram this is left out for relative clarity), an adjusting nut, two nyloc nuts and a G-cramp-style clamp welded to a long bar with a groove down it.

The device is clamped to the workpeice with the clamp described above. This clamp is welded only to the bar with the groove (about 6mm wide). Through this groove pass two studs (M6 threads at the end of each) which are welded to the main frame, and nyloc nuts keep these studs through the groove, but are not fully tightened such that the main frame can, via the studs, move up and down relative to the clamp, but not in any other direction.

The main frame splits into 3 parts, referred to here as 'top half', 'adjusting nut', and 'bottom half'. The top half has one of the aforementioned studs welded onto it, securing it into the groove. It has a bend of 90 degrees at the top and at the end of this there is a roller, shaped so that it will roll along the top of the tubular frame of a generic hacksaw (the profile could be altered for others, I would imagine, and perhaps a lever and spring for those whose frames are not parallel to the blade). The bottom of the top half is threaded for the adjusting nut.

The adjusting nut is a simple affair, being a nut, however one end has a right hand thread, and one has a LHT (to allow it to draw in/push out both sides at once).

The bottom half has a thread for this adjusting nut, and from there goes straight down for the width of a generic hacksaw (adjustable with the nut) where a rod is welded to it at 90 degrees, in the same direction as the top bend (perpendicular to the saw). I shall talk about this rod in more detail shortly. This piece (the bottom half) then undergoes a bend of 90 degrees just under the aforementioned rod.

The rod that is welded on is not any old rod; it has a coarse (male) helical thread on it, probably with at least 2 teeth(?) - like a classic DNA double helix. This can interlock with a similar female thread on the top roller - the declogger.

The declogger is a roller with teeth on it which engage with the profile of the saw teeth (labled anti-teeth in diagram), however these toothed sections are separated by toothless areas (labled grooves in the diagram, although they would be no deeper than the teeth to prevent the saw falling into them. The idea of this is that the teeth will roll with the saw blade while travelling longditudinally along the helical thread, pushing the swarf out of the teeth, and some into the 'grooves'.

To prevent the grooves between the anti-teeth from clogging, a third roller is placed beneath the de-clogger. This is in contact with the de-clogger and has a set of 'anti-anti-teeth' at one end only which engage with the de-clogger as a gear. This also has larger tooth-like protrusions which fit into the 'grooves' to clean them out. This is considerably smaller in diameter than the de-clogger so that the remaining swarf flies of more easily (rotating faster, greater acceleration of the roller away from the swarf - I think). This is mounted to the smooth axle at the bottom made by bending the main frame, as described previously. This allows it to move longditudinally with the declogging roller so that it can constantly mesh with it.

All three rollers are interchangable to match almost any standard blade/saw combination.

Having written all that, I strongly reccommend the use of the diagram in the [link].

TomP, Jan 27 2011

diagram http://www.flickr.c...058@N06/5393577833/
diagram of above invention [TomP, Jan 27 2011]

[link]






       I'm wondering whether there might be a simpler solution to the problem. For example, could you place a another sheet against the aluminium so that you cut both the aluminium and other sheet. The other sheet would be made of a material that draws the swarf out of the hacksaw teeth. Not sure what would be a suitable material; maybe plywood or a hard sponge material.
xaviergisz, Jan 27 2011
  

       I can't see how the assembly will follow the blade down as the cut is made. Did I miss that bit?
Ling, Jan 27 2011
  

       (+) for swarf.   

       I'm kind of [+/-] on the idea - but I really like the diagram. In fact, I think you should post a version that's sepia-toned and flipped horizontally.   

       (I did that, and it looks like something straight out of Leonardo's scratch pad)
lurch, Jan 28 2011
  

       [Ling] - I glossed over that a bit, but read the 4th paragraph again.   

       The sides of the groove constrain it in one direction, the (not tightened) nyloc nuts in the other direction so that the clamp assembly and the main frame assembly slide up and down, a bit like in a mitre saw, but they use two telescoping tubes instead of a groove.
TomP, Jan 28 2011
  

       Welcome, [TomP]. + for the idea.
++ for renewing my remembrance of "swarf."
csea, Jan 28 2011
  

       Welcome to HB - love the drawings... is there a dental version? [+]
xenzag, Jan 28 2011
  

       Could this also function as a guide for making straight cuts?
spidermother, Jan 29 2011
  

       Or you could use cutting fluid, which is acommon solution for this problem.
MechE, Jan 29 2011
  

       [MechE] - That's almost as boring a solution as changing the blade.   

       And I'm working on the dental version.
TomP, Jan 29 2011
  

       First I had to look up /swarf/ (that's what I love about this place!) and then I attempted to understand the diagram, but it seems very complicated...I would just dust off my hacksaw with my t-shirt...
(women DO use hacksaws you know!)
Welcome to the hb while I think about this more.
xandram, Jan 29 2011
  

       [+] for //anti-anti-teeth//   

       [Xandram] perhaps an upgrade would be a set of T-shirt fabric sleeves to put over the roller?
pocmloc, Jan 29 2011
  

       //And I'm working on the dental version.//   

       Special false teeth so you can chew the swarf off?
Ling, Jan 30 2011
  

       //I would just dust off my hacksaw with my t-shirt...//   

       Between each stroke?
TomP, Jan 30 2011
  
      
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