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Dan Hertzson

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  1. Dan Hertzson

    TW-90 motor

    Thanks so much for taking the time to check. I am reassured.
  2. Dan Hertzson

    TW-90 motor

    Strange question I admit, but I recently purchased a used TW-90 and am curious whether the original owner swapped out the motor. I believe that Travis uses both Leeson and Baldor motors, but am curious about the motor RPM. Mine runs very smoothly, but the motor is a 1750 RPM 2 HP motor. If anyone out there who has one of Travis's machines and is willing to check the RPM on the nameplate and get back to me I'd certainly appreciate it. Thanks Dan
  3. Dan Hertzson

    Quenchant amount q?

    Suggestions: Vertical quench: piece of 4 or 6" capped sch 40 PVC pipe Horizontal quench: aluminum turkey basting pan. Full blade quenches for either with oven snap temper then tempering tongs or torch to draw back spine if absolutely required.
  4. Dan Hertzson

    Bone handles

    From my limited experience with bone and antler I would strongly suggest you avoid exposing the pith/marrow, or even getting too close to it. It is very friable, and unless you plan on stabilizing it with a resin it will likely not hold up well.
  5. Dan Hertzson

    Hot fitting a wrought iron guard

    I'm considering hot fitting a wrought iron guard onto a hidden tang Bowie that I forged, ground and heat treated recently. This will be the first trial at hot fitting a guard on a knife (did it once on a sword in a class), but I wanted to try it this time because when I punched the guard while forging it I got a nice "dimple" on the blade side that I'd like to keep rather than grinding that surface flush. What I'm trying to figure out is how close to the ricasso I should file the slot before hot fitting. The taper angle on the tang is fairly standard (maybe 15 degrees, though I don't have it with me right now, and I currently have it cold fitting down to around 3/4" from the final resting place). I could probably do the math for thermal expansion ratio and the like, but there are a couple of variables that are not necessarily clear (like how much drifting of the slot can be expected from hammering it into place). Any experienced folk have a general rule of thumb for this? I'd like to get it close before I do the final shaping on the guard. Thanks.
  6. Dan Hertzson

    Propane Fume Extraction in an Ancient Small Shop

    As propane is nominally heavier than air, the ideal fume extraction from your shop will have both high and low inlet points to handle both the heated combustion products and a potential propane leak (I burn natural gas, so only have a high exhaust). I personally have a 20 x 20 shop and use an almost 10,000 CFM, 1/2 HP sidewall exhaust fan and run a ton of air through my shop. This type of fan is ideal for the application, high volume and low static. More is definitely better, and my general assumption is that you don't need a hood with a natural gas forge as both the hot exhaust products and any leakage should rise. My fan is placed in the sidewall of the shop, high up in the roof peak. You certainly don't need anywhere near that much ventilation, but I find that it also helps keep the shop a little cooler.
  7. Dan Hertzson

    Propane Fume Extraction in an Ancient Small Shop

    You may not necessarily need to go with an expensive BIF Axial fan. A centrifugal utility set fan will also have the motor out of the airstream and can often be sourced at liquidators. You will need to be more creative about the duct runs, as they are not inline fans, but it should still work for you (there are also less expensive inline centrifugal fans that are belt driven, with the motor out of the airstream, but those are less common. Note that for fume extraction you don't necessarily need to worry, but if you are anticipating any kind of dust (in particular wood dust or a combination of same with metal dust) I would look carefully into spark/explosion proof fans, spark arrestors, a water trap... A good rule of thumb for capture of fumes is to have at least 100 ft./min. at the crossection of the hood entrance (i.e. if you have a 2' x 4' hood inlet you should pull 800 CFM at the fan and typically use a 12" diameter duct to connect them, the last depending on the external static pressure the fan will exert). A louver in a window or door will allow the makeup air you need to compensate for the exhaust. Typical velocities to avoid entraining weather are in the neighborhood of 500 FPM for a conventional louver and 800 FPM for a special drainable louver.
  8. Dan Hertzson

    Mini-Anvils, Possibly For Sale

    Any chance you could make some with a hardy post cast in place on the bottom (perhaps leaving a sprue or similar)? Would make a lovely usable tool...
  9. Dan Hertzson

    FLat bar tongs for sale.

    Also have a pair that I bought at the last Ashokan. They work great and I wish I had gotten one in each size.
  10. Dan Hertzson

    Easy Beginner Forge

    Not sure why you posted a picture of a solid fuel coal forge when you wanted to make a gas forge. That is why you got feedback for the former option. Propane forges should be lined with a material that has a decent insulating value and can stand up to gas forging temperatures (i.e. up to 2400 deg. F for forge welding and potentially over 3,000 deg. F for the flame impingement zone). Neither clay nor the plaster or paris/sand mix are acceptable options IMHO. Those materials are better for solid fuel forges, though the plaster is a bad choice for those as well. I like to use 2" of high temperature insulating ceramic blanket (Kaowool) and a castable refractory inner liner (Kastolite), but there are plenty of other options. See this site for more detail: https://www.iforgeiron.com/forum/65-gas-forges/ Note that the more successful coffee can forges I've seen run on Mapp gas torches, not propane as well.
  11. Dan Hertzson

    The Gambler

    Lovely work. Looks very period. This is a beginner question I know, but I'm just getting started making knives with multiple pins and still struggle with alignment. Do all 49 of those pins go all the way through the tang as well or are most of them surface inlays for decoration? If they penetrate all the way through are you drilling the tang very oversized to allow the precision drilling of the handle after the blade is heat treated? I guess I'm just interested in your handle construction and assembly sequence. Thanks in advance for any tips.
  12. Dan Hertzson

    Blade 2 for me

    Might get more contrast if you cut through the layers to expose the alternate colors. Looks like your cut cloth pieces are a little large for flat slab sides. Otherwise nice on for a second knife to be sure. Keep on plugging.
  13. Dan Hertzson

    Trouble heat treating file knives

    A couple of questions that may help diagnosis: What kind of oil and what temperature was the oil at each time? How are you determining what temperature the blank is before quenching? How did you monitor the kitchen oven temperature (just the dial on the face or an actual thermometer)? By the color and hardness you got it would appear you got it too hot. What was the maximum and minimum thickness of the blades before hardening? How long did you hold the blanks at the pre-quench temperature before the second quench, and how long did it take to get up to temperature (possible decarb if too long at heat)? Did you normalize again before the second quench?
  14. Dan Hertzson

    My newest

    Nice riggers knife
  15. Dan Hertzson

    Angle Grinder vs Leg - who wins? Graphic!

    Yikes, glad to hear that you will recover. Hope you are back on your feet soon. This is why I only have paddle switch style angle grinders in my shop, though I have to admit I'm not always as careful as I should be in setting them down on a cluttered table top where they might fall over and engage said switch. Thanks for the cautionary tale to help keep the rest of us on guard as well.
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